Triplet excitons in organic molecules underscore a variety of processes and technologies as a result of their long lifetime and spin multiplicity. Organic phosphorescence, which originates from triplet excitons, has potential for the development of a new generation of organic optoelectronic materials and biomedical agents. However, organic phosphorescence is typically only observed at cryogenic temperatures and under inert conditions in solution, which severely restricts its practical applications. In the past few years, room-temperature-phosphorescent systems have been obtained based on organic aggregates. Rapid advances in molecular-structure design and aggregation-behaviour modulation have enabled substantial progress, but the mechanistic picture is still not fully understood because of the high sensitivity and complexity of triplet-exciton behaviour. This Review analyses key photophysical processes related to triplet excitons, including intersystem crossing, radiative and non-radiative decay, and quenching processes, to illustrate the intrinsic structure–property relationships and draw clear and integrated design principles. The resulting strategies for the development of efficient and persistent room-temperature-phosphorescent systems are discussed, and newly emerged applications based on these materials are highlighted.
Subscribe to Journal
Get full journal access for 1 year
only $4.92 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Rent or Buy article
Get time limited or full article access on ReadCube.
All prices are NET prices.
Baldo, M. A. et al. Highly efficient phosphorescent emission from organic electroluminescent devices. Nature 395, 151–154 (1998).
Xu, H. et al. Recent progress in metal–organic complexes for optoelectronic applications. Chem. Soc. Rev. 43, 3259–3302 (2014).
Weissleder, R. A clearer vision for in vivo imaging. Nat. Biotechnol. 19, 316–317 (2001).
Mei, J. et al. Aggregation-induced emission: the whole is more brilliant than the parts. Adv. Mater. 26, 5429–5479 (2014).
Kabe, R. & Adachi, C. Organic long persistent luminescence. Nature 550, 384–387 (2017).
Uoyama, H., Goushi, K., Shizu, K., Nomura, H. & Adachi, C. Highly efficient organic light-emitting diodes from delayed fluorescence. Nature 492, 234–238 (2012).
Liu, Y., Li, C., Ren, Z., Yan, S. & Bryce, M. R. All-organic thermally activated delayed fluorescence materials for organic light-emitting diodes. Nat. Rev. Mater. 3, 18020 (2018).
Zheng, X. et al. Hypoxia-specific ultrasensitive detection of tumours and cancer cells in vivo. Nat. Commun. 6, 5834 (2015).
Lewis, G. N. & Kasha, M. Phosphorescence and the triplet state. J. Am. Chem. Soc. 66, 2100–2116 (1944). This pioneering publication identified the phosphorescence of an organic molecule as a radiative transition from the lowest triplet state.
Lower, S. & El-Sayed, M. The triplet state and molecular electronic processes in organic molecules. Chem. Rev. 66, 199–241 (1966). This work systematically analyses the radiative and non-radiative properties of the triplet state, especially the El-Sayed rule for intersystem crossing process.
Wise, D. L. Electrical and Optical Polymer Systems: Fundamentals: Methods, and Applications (CRC, 1998).
Turro, N. J., Ramamurthy, V. & Scaiano, J. C. Modern Molecular Photochemistry of Organic Molecules (Viva Books, University Science Books, 2017).
Marian, C. M. Spin–orbit coupling and intersystem crossing in molecules. Wiley Interdiscip. Rev. Comput. Mol. Sci. 2, 187–203 (2012).
Baryshnikov, G., Minaev, B. & Ågren, H. Theory and calculation of the phosphorescence phenomenon. Chem. Rev. 117, 6500–6537 (2017).
Lewis, G. N., Lipkin, D. & Magel, T. T. Reversible photochemical processes in rigid media. A study of the phosphorescent state. J. Am. Chem. Soc. 63, 3005–3018 (1941).
Kuijt, J., Ariese, F., Udo, A. T. & Gooijer, C. Room temperature phosphorescence in the liquid state as a tool in analytical chemistry. Anal. Chim. Acta 488, 135–171 (2003).
Yuan, W. Z. et al. Crystallization-induced phosphorescence of pure organic luminogens at room temperature. J. Phys. Chem. C 114, 6090–6099 (2010). This work reported crystallization-induced phosphorescence in pure organic compounds at room temperature.
Bilen, C. S., Harrison, N. & Morantz, D. J. Unusual room temperature afterglow in some crystalline organic compounds. Nature 271, 235–237 (1978).
Schulman, E. M. & Walling, C. Phosphorescence of adsorbed ionic organic molecules at room temperature. Science 178, 53–54 (1972).
Mei, J., Leung, N. L., Kwok, R. T., Lam, J. W. & Tang, B. Z. Aggregation-induced emission: together we shine, united we soar! Chem. Rev. 115, 11718–11940 (2015).
An, Z. et al. Stabilizing triplet excited states for ultralong organic phosphorescence. Nat. Mater. 14, 685–690 (2015). This work reports a series of pure organic materials with persistent RTP.
Baroncini, M., Bergamini, G. & Ceroni, P. Rigidification or interaction-induced phosphorescence of organic molecules. Chem. Commun. 53, 2081–2093 (2017).
Yuasa, H. & Kuno, S. Intersystem crossing mechanisms in the room temperature phosphorescence of crystalline organic compounds. Bull. Chem. Soc. Jpn. 91, 223–229 (2018).
Xu, S., Chen, R., Zheng, C. & Huang, W. Excited state modulation for organic afterglow: materials and applications. Adv. Mater. 28, 9920–9940 (2016).
Ward, J. S. et al. The interplay of thermally activated delayed fluorescence (TADF) and room temperature organic phosphorescence in sterically-constrained donor–acceptor charge-transfer molecules. Chem. Commun. 52, 2612–2615 (2016).
Shuai, Z. & Peng, Q. Excited states structure and processes: understanding organic light-emitting diodes at the molecular level. Phys. Rep. 537, 123–156 (2014).
Ma, H. et al. Room-temperature phosphorescence in metal-free organic materials. Ann. Phys. 531, 1800482 (2019).
Henry, B. R. & Siebrand, W. Spin–orbit coupling in aromatic hydrocarbons. Analysis of nonradiative transitions between singlet and triplet states in benzene and naphthalene. J. Chem. Phys. 54, 1072–1085 (1971).
Gong, Y. et al. Crystallization-induced dual emission from metal- and heavy atom-free aromatic acids and esters. Chem. Sci. 6, 4438–4444 (2015).
Li, C. Y. et al. Reversible luminescence switching of an organic solid: controllable on–off persistent room temperature phosphorescence and stimulated multiple fluorescence conversion. Adv. Opt. Mater. 3, 1184–1190 (2015).
Zhao, W. et al. Rational molecular design for achieving persistent and efficient pure organic room-temperature phosphorescence. Chem 1, 592–602 (2016). This study provides a systematic discussion of the intrinsic relationship between molecular structure and RTP performance, and presents efficient and persistent room-temperature-phosphorescent materials.
Xue, P., Wang, P., Chen, P., Ding, J. & Lu, R. Enhanced room-temperature phosphorescence of triphenylphosphine derivatives without metal and heavy atoms in their crystal phase. RSC Adv. 6, 51683–51686 (2016).
Hamzehpoor, E. & Perepichka, D. F. Crystal engineering of room temperature phosphorescence in organic solids. Angew. Chem. Int. Ed. 59, 9977–9981 (2020).
Shimizu, M. et al. Siloxy group-induced highly efficient room temperature phosphorescence with long lifetime. J. Phys. Chem. C 120, 11631–11639 (2016).
Xu, B. et al. White-light emission from a single heavy atom-free molecule with room temperature phosphorescence, mechanochromism and thermochromism. Chem. Sci. 8, 1909–1914 (2017).
Zhou, C. et al. Ternary emission of fluorescence and dual phosphorescence at room temperature: a single-molecule white light emitter based on pure organic aza-aromatic material. Adv. Funct. Mater. 28, 1802407 (2018).
Yuan, J. et al. Invoking ultralong room temperature phosphorescence of purely organic compounds through H-aggregation engineering. Mater. Horiz. 6, 1259–1264 (2019).
Fermi, A., Bergamini, G., Roy, M., Gingras, M. & Ceroni, P. Turn-on phosphorescence by metal coordination to a multivalent terpyridine ligand: a new paradigm for luminescent sensors. J. Am. Chem. Soc. 136, 6395–6400 (2014).
Riebe, S. et al. Aromatic thioethers as novel luminophores with aggregation-induced fluorescence and phosphorescence. Chem. Eur. J. 23, 13660–13668 (2017).
Yu, Z. et al. Organic phosphorescence nanowire lasers. J. Am. Chem. Soc. 139, 6376–6381 (2017).
Tao, Y. et al. Resonance-activated spin-flipping for efficient organic ultralong room-temperature phosphorescence. Adv. Mater. 30, 1803856 (2018).
Takeda, Y. et al. Conformationally-flexible and moderately electron-donating units-installed D–A–D triad enabling multicolor-changing mechanochromic luminescence, TADF and room-temperature phosphorescence. Chem. Commun. 54, 6847–6850 (2018).
Ceroni, P. Design of phosphorescent organic molecules: old concepts under a new light. Chem 1, 524–526 (2016).
Ma, H., Peng, Q., An, Z., Huang, W. & Shuai, Z. Efficient and long-lived room-temperature organic phosphorescence: theoretical descriptors for molecular designs. J. Am. Chem. Soc. 141, 1010–1015 (2018).
Hadley, S. G. & Keller, R. A. Direct determination of the singlet. far. triplet intersystem crossing quantum yield in naphthalene, phenanthrene, and triphenylene. J. Phys. Chem. 73, 4356–4359 (1969).
Lamola, A. A. & Hammond, G. S. Mechanisms of photochemical reactions in solution. XXXIII. Intersystem crossing efficiencies. J. Chem. Phys. 43, 2129–2135 (1965).
Shoji, Y. et al. Unveiling a new aspect of simple arylboronic esters: long-lived room-temperature phosphorescence from heavy-atom-free molecules. J. Am. Chem. Soc. 139, 2728–2733 (2017).
Torres Delgado, W. et al. Moving beyond boron-based substituents to achieve phosphorescence in tellurophenes. ACS Appl. Mater. Interfaces 10, 12124–12134 (2017).
Li, M. et al. Achieving high-efficiency purely organic room-temperature phosphorescence materials by boronic ester substitution of phenoxathiine. Chem. Commun. 55, 7215–7218 (2019).
Zhou, Y. et al. Long-lived room-temperature phosphorescence for visual and quantitative detection of oxygen. Angew. Chem. Int. Ed. 58, 12102–12106 (2019).
Li, M. et al. Prolonging ultralong organic phosphorescence lifetime to 2.5s through confining rotation in molecular rotor. Adv. Opt. Mater. 7, 1800820 (2019).
Salla, C. A. M. et al. Persistent solid-state phosphorescence and delayed fluorescence at room temperature by a twisted hydrocarbon. Angew. Chem. Int. Ed. 58, 6982–6986 (2019).
Schmidt, K. et al. Intersystem crossing processes in nonplanar aromatic heterocyclic molecules. J. Phys. Chem. A 111, 10490–10499 (2007).
Penfold, T. J., Gindensperger, E., Daniel, C. & Marian, C. M. Spin-vibronic mechanism for intersystem crossing. Chem. Rev. 118, 6975–7025 (2018).
Wen, Y. et al. One-dimensional π–π stacking induces highly efficient pure organic room-temperature phosphorescence and ternary-emission single-molecule white light. J. Mater. Chem. C 7, 12502–12508 (2019).
Shi, H. et al. Enhancing organic phosphorescence by manipulating heavy-atom interaction. Cryst. Growth Des. 16, 808–813 (2016).
Xiao, L. et al. Highly efficient room-temperature phosphorescence from halogen-bonding-assisted doped organic crystals. J. Phys. Chem. A 121, 8652–8658 (2017).
Xu, L. et al. Chalcogen atom modulated persistent room-temperature phosphorescence through intramolecular electronic coupling. Chem. Commun. 54, 9226–9229 (2018).
He, G. et al. Coaxing solid-state phosphorescence from tellurophenes. Angew. Chem. Int. Ed. 126, 4675–4679 (2014).
Mao, Z. et al. Linearly tunable emission colors obtained from a fluorescent–phosphorescent dual-emission compound by mechanical stimuli. Angew. Chem. Int. Ed. 54, 6270–6273 (2015).
Shi, H. et al. Highly efficient ultralong organic phosphorescence through intramolecular-space heavy-atom effect. J. Phys. Chem. Lett. 10, 595–600 (2019).
Wang, J. et al. A facile strategy for realizing room temperature phosphorescence and single molecule white light emission. Nat. Commun. 9, 2963 (2018).
Xiao, L. & Fu, H. Enhanced room-temperature phosphorescence through intermolecular halogen/hydrogen bonding. Chem. Eur. J. 25, 714–723 (2019).
Gao, H. Y. et al. Phosphorescent co-crystal assembled by 1,4-diiodotetrafluorobenzene with carbazole based on C–I···π halogen bonding. J. Mater. Chem. 22, 5336–5343 (2012).
Cai, S. et al. Enhancing ultralong organic phosphorescence by effective π-type halogen bonding. Adv. Funct. Mater. 28, 1705045 (2018).
Shen, Q. J. et al. Phosphorescent cocrystals constructed by 1,4-diiodotetrafluorobenzene and polyaromatic hydrocarbons based on C–I···π halogen bonding and other assisting weak interactions. CrystEngComm 14, 5027–5034 (2012).
Bolton, O., Lee, K., Kim, H. J., Lin, K. Y. & Kim, J. Activating efficient phosphorescence from purely organic materials by crystal design. Nat. Chem. 3, 205–210 (2011). This work details the design of a highly efficient room-temperature-phosphorescent system based on crystal engineering by the incorporation of halogen bonding.
Maity, S. K., Bera, S., Paikar, A., Pramanik, A. & Haldar, D. Halogen bond induced phosphorescence of capped γ-amino acid in the solid state. Chem. Commun. 49, 9051–9053 (2013).
Buck, J. T. et al. Spin-allowed transitions control the formation of triplet excited states in orthogonal donor-acceptor dyads. Chem 5, 138–155 (2019).
Kuno, S., Akeno, H., Ohtani, H. & Yuasa, H. Visible room-temperature phosphorescence of pure organic crystals via a radical-ion-pair mechanism. Phys. Chem. Chem. Phys. 17, 15989–15995 (2015).
Kuno, S., Kanamori, T., Yijing, Z., Ohtani, H. & Yuasa, H. Long persistent phosphorescence of crystalline phenylboronic acid derivatives: photophysics and a mechanistic study. ChemPhotoChem 1, 102–106 (2017).
Matsuoka, H. et al. Time-resolved electron paramagnetic resonance and theoretical investigations of metal-free room-temperature triplet emitters. J. Am. Chem. Soc. 139, 12968–12975 (2017).
Bhatia, H., Bhattacharjee, I. & Ray, D. Biluminescence via fluorescence and persistent phosphorescence in amorphous organic donor (D4)–acceptor (A) conjugates and application in data security protection. J. Phys. Chem. Lett. 9, 3808–3813 (2018).
Xiong, Y. et al. Designing efficient and ultralong pure organic room-temperature phosphorescent materials by structural isomerism. Angew. Chem. Int. Ed. 57, 7997–8001 (2018).
Zhang, X. et al. General design strategy for aromatic ketone-based single-component dual-emissive materials. ACS Appl. Mater. Interfaces 6, 2279–2284 (2014).
Chen, X. et al. Versatile room-temperature-phosphorescent materials prepared from N-substituted naphthalimides: emission enhancement and chemical conjugation. Angew. Chem. Int. Ed. 55, 9872–9876 (2016).
Huang, W., Chen, B. & Zhang, G. Persistent room-temperature radicals from anionic naphthalimides: spin pairing and supramolecular chemistry. Chem. Eur. J. 25, 12497–12501 (2019).
Yang, Z. et al. Intermolecular electronic coupling of organic units for efficient persistent room-temperature phosphorescence. Angew. Chem. Int. Ed. 55, 2181–2185 (2016).
Bhattacharjee, I., Acharya, N., Karmakar, S. & Ray, D. Room-temperature orange-red phosphorescence by way of intermolecular charge transfer in single-component phenoxazine–quinoline conjugates and chemical sensing. J. Phys. Chem. C 122, 21589–21597 (2018).
Li, F. et al. Achieving dual persistent room-temperature phosphorescence from polycyclic luminophores via inter-/intramolecular charge transfer. Adv. Opt. Mater. 7, 1900511 (2019).
Mao, Z. et al. Two-photon-excited ultralong organic room temperature phosphorescence by operating dual-channel triplet harvesting. Chem. Sci. 10, 7352–7357 (2019).
Lei, Y. X. et al. Revealing insight into long-lived room-temperature phosphorescence of host-guest systems. J. Phys. Chem. Lett. 10, 6019–6025 (2019).
Etherington, M. K., Gibson, J., Higginbotham, H. F., Penfold, T. J. & Monkman, A. P. Revealing the spin–vibronic coupling mechanism of thermally activated delayed fluorescence. Nat. Commun. 7, 13680 (2016).
Yu, L. et al. Pure organic emitter with simultaneous thermally activated delayed fluorescence and room-temperature phosphorescence: thermal-controlled triplet recycling channels. Adv. Opt. Mater. 5, 1700588 (2017).
Chen, C. et al. Intramolecular charge transfer controls switching between room temperature phosphorescence and thermally activated delayed fluorescence. Angew. Chem. Int. Ed. 130, 16645–16649 (2018).
Ward, J. S. et al. Bond rotations and heteroatom effects in donor–acceptor–donor molecules: implications for thermally activated delayed fluorescence and room temperature phosphorescence. J. Org. Chem. 83, 14431–14442 (2018).
Han, H. & Kim, E. G. Dielectric effects on charge-transfer and local excited states in organic persistent room-temperature phosphorescence. Chem. Mater. 31, 6925–6935 (2019).
Kukhta, N. A., Huang, R., Batsanov, A. S., Bryce, M. R. & Dias, F. B. Achieving conformational control in RTP and TADF emitters by functionalization of the central core. J. Phys. Chem. C 123, 26536–26546 (2019).
Ward, J. S. et al. Impact of methoxy substituents on thermally activated delayed fluorescence and room-temperature phosphorescence in all-organic donor–acceptor systems. J. Org. Chem. 84, 3801–3816 (2019).
Bhattacharjee, I., Acharya, N. & Ray, D. Thermally activated delayed fluorescence and room-temperature phosphorescence in naphthyl appended carbazole–quinoline conjugates, and their mechanical regulation. Chem. Commun. 55, 1899–1902 (2019).
Chen, J. et al. Achieving dual-emissive and time-dependent evolutive organic afterglow by bridging molecules with weak intermolecular hydrogen bonding. Adv. Opt. Mater. 7, 1801593 (2019).
Data, P., Okazaki, M., Minakata, S. & Takeda, Y. Thermally activated delayed fluorescence vs. room temperature phosphorescence by conformation control of organic single molecules. J. Mater. Chem. C 7, 6616–6621 (2019).
Data, P. & Takeda, Y. Recent advancements in and the future of organic emitters: TADF- and RTP-active multifunctional organic materials. Chem. Asian J. 14, 1613–1636 (2019).
Yang, L. et al. Aggregation-induced intersystem crossing: a novel strategy for efficient molecular phosphorescence. Nanoscale 8, 17422–17426 (2016).
Sun, X. et al. Polymerization-enhanced intersystem crossing: new strategy to achieve long-lived excitons. Macromol. Rapid Commun. 36, 298–303 (2015).
Kasha, M., Rawls, H. R. & El-Bayoumi, M. A. The exciton model in molecular spectroscopy. Pure Appl. Chem. 11, 371–392 (1965).
Lucenti, E. et al. Cyclic triimidazole derivatives: intriguing examples of multiple emissions and ultralong phosphorescence at room temperature. Angew. Chem. Int. Ed. 56, 16302–16307 (2017).
Yang, J. et al. The influence of the molecular packing on the room temperature phosphorescence of purely organic luminogens. Nat. Commun. 9, 840 (2018).
Wu, H. et al. Crystal multi-conformational control through deformable carbon-sulfur bond for singlet-triplet emissive tuning. Angew. Chem. Int. Ed. 22, 4372–4377 (2019).
Zhao, W. et al. Highly sensitive switching of solid-state luminescence by controlling intersystem crossing. Nat. Commun. 9, 3044 (2018).
Gao, R. & Yan, D. Layered host–guest long-afterglow ultrathin nanosheets: high-efficiency phosphorescence energy transfer at 2D confined interface. Chem. Sci. 8, 590–599 (2017).
Hirata, S., Totani, K., Yamashita, T., Adachi, C. & Vacha, M. Large reverse saturable absorption under weak continuous incoherent light. Nat. Mater. 13, 938–946 (2014).
Notsuka, N., Kabe, R., Goushi, K. & Adachi, C. Confinement of long-lived triplet excitons in organic semiconducting host–guest systems. Adv. Funct. Mater. 27, 1703902 (2017).
Zhao, W. et al. Boosting the efficiency of organic persistent room-temperature phosphorescence by intramolecular triplet-triplet energy transfer. Nat. Commun. 10, 1595 (2019).
Huang, R. et al. The influence of molecular conformation on the photophysics of organic room temperature phosphorescent luminophores. J. Mater. Chem. C 6, 9238–9247 (2018).
Breen, D. E. & Keller, R. A. Intramolecular energy transfer between triplet states of weakly interacting chromophores. I. Compounds in which the chromophores are separated by a series of methylene groups. J. Am. Chem. Soc. 90, 1935–1940 (1968).
Ma, H. et al. Electrostatic interaction-induced room-temperature phosphorescence in pure organic molecules from QM/MM calculations. J. Phys. Chem. Lett. 7, 2893–2898 (2016).
Hirata, S. Intrinsic analysis of radiative and room-temperature nonradiative processes based on triplet state intramolecular vibrations of heavy atom-free conjugated molecules toward efficient persistent room-temperature phosphorescence. J. Phys. Chem. Lett. 9, 4251–4259 (2018).
Hayduk, M., Riebe, S. & Voskuhl, J. Phosphorescence through hindered motion of pure organic emitters. Chem. Eur. J. 24, 12221–12230 (2018).
Schulman, E. M. & Parker, R. T. Room temperature phosphorescence of organic compounds. The effects of moisture, oxygen, and the nature of the support-phosphor interaction. J. Phys. Chem. 81, 1932–1939 (1977).
Ma, X., Wang, J. & Tian, H. Assembling-induced emission: an efficient approach for amorphous metal-free organic emitting materials with room-temperature phosphorescence. Acc. Chem. Res. 52, 738–748 (2019). This work reviews assembling strategies for the realization of organic materials exhibiting RTP.
Yong, G.-P., Zhang, Y.-M., She, W.-L. & Li, Y.-Z. Stacking-induced white-light and blue-light phosphorescence from purely organic radical materials. J. Mater. Chem. 21, 18520–18522 (2011).
Gong, Y. et al. Achieving persistent room temperature phosphorescence and remarkable mechanochromism from pure organic luminogens. Adv. Mater. 27, 6195–6201 (2015).
Chen, G. L., Guo, S. D., Feng, H. & Qian, Z. S. Anion-regulated transient and persistent phosphorescence and size-dependent ultralong afterglow of organic ionic crystals. J. Mater. Chem. C 7, 14535–14542 (2019).
Shen, Q. J., Wei, H. Q., Zou, W. S., Sun, H. L. & Jin, W. J. Cocrystals assembled by pyrene and 1,2- or 1,4-diiodotetrafluorobenzenes and their phosphorescent behaviors modulated by local molecular environment. CrystEngComm 14, 1010–1015 (2012).
Bian, L. et al. Simultaneously enhancing efficiency and lifetime of ultralong organic phosphorescence materials by molecular self-assembly. J. Am. Chem. Soc. 140, 10734–10739 (2018).
Wu, H. et al. Molecular stacking dependent phosphorescence–fluorescence dual emission in a single luminophore for self-recoverable mechanoconversion of multicolor luminescence. Chem. Commun. 53, 2661–2664 (2017).
Wu, H. et al. Tuning for visible fluorescence and near-infrared phosphorescence on a unimolecular mechanically sensitive platform via adjustable CH− π interaction. ACS Appl. Mater. Interfaces 9, 3865–3872 (2017).
Wu, H. et al. Helical self-assembly-induced singlet–triplet emissive switching in a mechanically sensitive system. J. Am. Chem. Soc. 139, 785–791 (2017).
Zhou, B. & Yan, D. Hydrogen-bonded two-component ionic crystals showing enhanced long-lived room-temperature phosphorescence via TADF-assisted Förster resonance energy transfer. Adv. Funct. Mater. 29, 1807599 (2019).
Lee, D. et al. Room temperature phosphorescence of metal-free organic materials in amorphous polymer matrices. J. Am. Chem. Soc. 135, 6325–6329 (2013).
Sternlicht, H., Nieman, G. & Robinson, G. Triplet — triplet annihilation and delayed fluorescence in molecular aggregates. J. Chem. Phys. 38, 1326–1335 (1963).
Hirata, S. Recent advances in materials with room-temperature phosphorescence: photophysics for triplet exciton stabilization. Adv. Opt. Mater. 5, 1700116 (2017).
Liu, D. K. & Faulkner, L. R. Delayed fluorescence efficiencies of anthracene and phenanthrene. J. Am. Chem. Soc. 100, 2635–2639 (1978).
Chen, H., Yao, X., Ma, X. & Tian, H. Amorphous, efficient, room-temperature phosphorescent metal-free polymers and their applications as encryption ink. Adv. Opt. Mater. 4, 1397–1401 (2016).
Ogoshi, T. et al. Ultralong room-temperature phosphorescence from amorphous polymer poly(styrene sulfonic acid) in air in the dry solid state. Adv. Funct. Mater. 28, 1707369 (2018).
Cai, S. et al. Enabling long-lived organic room temperature phosphorescence in polymers by subunit interlocking. Nat. Commun. 10, 4247 (2019).
Zhang, Y.-F. et al. Isophthalate-based room temperature phosphorescence: from small molecule to side-chain jacketed liquid crystalline polymer. Macromolecules 52, 2495–2503 (2019).
Chen, X. et al. Aggregation-induced dual emission and unusual luminescence beyond excimer emission of poly(ethylene terephthalate). Macromolecules 51, 9035–9042 (2018).
Kanosue, K. et al. A colorless semi-aromatic polyimide derived from a sterically hindered bromine-substituted dianhydride exhibiting dual fluorescence and phosphorescence emission. Mater. Chem. Front. 3, 39–49 (2019).
Zhang, G. et al. Multi-emissive difluoroboron dibenzoylmethane polylactide exhibiting intense fluorescence and oxygen-sensitive room-temperature phosphorescence. J. Am. Chem. Soc. 129, 8942–8943 (2007).
Kwon, M. S. et al. Suppressing molecular motions for enhanced room-temperature phosphorescence of metal-free organic materials. Nat. Commun. 6, 8947 (2015).
Yu, Y. et al. Room-temperature-phosphorescence-based dissolved oxygen detection by core-shell polymer nanoparticles containing metal-free organic phosphors. Angew. Chem. Int. Ed. 56, 16207–16211 (2017).
Ma, X., Xu, C., Wang, J. & Tian, H. Amorphous pure organic polymers for heavy-atom-free efficient room-temperature phosphorescence emission. Angew. Chem. Int. Ed. 57, 10854–10858 (2018).
Fang, M.-M., Yang, J. & Li, Z. Recent advances in purely organic room temperature phosphorescence polymer. Chin. J. Polym. Sci. 37, 383–393 (2019).
Gan, N., Shi, H., An, Z. & Huang, W. Recent advances in polymer-based metal-free room-temperature phosphorescent materials. Adv. Funct. Mater. 28, 1802657 (2018).
Turro, N. J. & Aikawa, M. Phosphorescence and delayed fluorescence of 1-chloronaphthalene in micellar solutions. J. Am. Chem. Soc. 102, 4866–4870 (1980).
Nazarov, V., Gerko, V. & Alfimov, M. Nature of the room-temperature phosphorescence of cyclodextrin-aromatic compound complexes in water. Russ. Chem. Bull. 45, 969–970 (1996).
Ma, X., Cao, J., Wang, Q. & Tian, H. Photocontrolled reversible room temperature phosphorescence (RTP) encoding β-cyclodextrin pseudorotaxane. Chem. Commun. 47, 3559–3561 (2011).
Li, D. et al. Amorphous metal-free room-temperature phosphorescent small molecules with multicolor photoluminescence via a host–guest and dual-emission strategy. J. Am. Chem. Soc. 140, 1916–1923 (2018).
Zhang, Z.-Y., Chen, Y. & Liu, Y. Efficient room-temperature phosphorescence of a solid-state supramolecule enhanced by cucurbituril. Angew. Chem. Int. Ed. 131, 6089–6093 (2019).
Ishida, Y., Shimada, T., Ramasamy, E., Ramamurthy, V. & Takagi, S. Room temperature phosphorescence from a guest molecule confined in the restrictive space of an organic–inorganic supramolecular assembly. Photochem. Photobiol. Sci. 15, 959–963 (2016).
Hirata, S. et al. Efficient persistent room temperature phosphorescence in organic amorphous materials under ambient conditions. Adv. Funct. Mater. 23, 3386–3397 (2013). This study introduced a smart host–guest approach for the rational design of efficient and persistent room-temperature-phosphorescent materials.
Hirata, S. et al. Reversible thermal recording media using time-dependent persistent room temperature phosphorescence. Adv. Opt. Mater. 1, 438–442 (2013).
Hirata, S. & Vacha, M. Circularly polarized persistent room-temperature phosphorescence from metal-free chiral aromatics in air. J. Phys. Chem. Lett. 7, 1539–1545 (2016).
Hirata, S., Totani, K., Watanabe, T., Kaji, H. & Vacha, M. Relationship between room temperature phosphorescence and deuteration position in a purely aromatic compound. Chem. Phys. Lett. 591, 119–125 (2014).
Wei, J. et al. Induction of strong long-lived room-temperature phosphorescence of N-phenyl-2-naphthylamine molecules by confinement in a crystalline dibromobiphenyl matrix. Angew. Chem. Int. Ed. 55, 15589–15593 (2016).
Mieno, H., Kabe, R., Notsuka, N., Allendorf, M. D. & Adachi, C. Long-lived room-temperature phosphorescence of coronene in zeolitic imidazolate framework ZIF-8. Adv. Opt. Mater. 4, 1015–1021 (2016).
Yang, X. & Yan, D. Strongly enhanced long-lived persistent room temperature phosphorescence based on the formation of metal–organic hybrids. Adv. Opt. Mater. 4, 897–905 (2016).
Ford, C. D. & Hurtubise, R. J. Room-temperature phosphorescence of the phthalic acid isomers, p-aminobenzoic acid, and terephthalamide adsorbed on silica gel. Anal. Chem. 50, 610–612 (1978).
Joseph, J. & Anappara, A. A. Cool white, persistent room-temperature phosphorescence in carbon dots embedded in a silica gel matrix. Phys. Chem. Chem. Phys. 19, 15137–15144 (2017).
Gao, R., Mei, X., Yan, D., Liang, R. & Wei, M. Nano-photosensitizer based on layered double hydroxide and isophthalic acid for singlet oxygenation and photodynamic therapy. Nat. Commun. 9, 2798 (2018).
Wang, B. et al. Red room-temperature phosphorescence of CDs@ zeolite composites triggered by heteroatoms in zeolite frameworks. ACS Cent. Sci. 5, 349–356 (2019).
Louis, M. et al. Blue-light-absorbing thin films showing ultralong room-temperature phosphorescence. Adv. Mater. 31, 1807887 (2019).
Al-Attar, H. A. & Monkman, A. P. Room-temperature phosphorescence from films of isolated water-soluble conjugated polymers in hydrogen-bonded matrices. Adv. Funct. Mater. 22, 3824–3832 (2012).
Kwon, M. S., Lee, D., Seo, S., Jung, J. & Kim, J. Tailoring intermolecular interactions for efficient room-temperature phosphorescence from purely organic materials in amorphous polymer matrices. Angew. Chem. Int. Ed. 53, 11177–11181 (2014).
Su, Y. et al. Ultralong room temperature phosphorescence from amorphous organic materials toward confidential information encryption and decryption. Sci. Adv. 4, eaas9732 (2018).
Tian, Z. et al. Multilevel data encryption using thermal-treatment controlled room temperature phosphorescence of carbon dot/polyvinylalcohol composites. Adv. Sci. 5, 1800795 (2018).
Wu, H. et al. Achieving amorphous ultralong room temperature phosphorescence by coassembling planar small organic molecules with polyvinyl alcohol. Adv. Funct. Mater. 29, 1807243 (2019).
Deng, Y. et al. Long lifetime pure organic phosphorescence based on water soluble carbon dots. Chem. Commun. 49, 5751–5753 (2013). This work constitutes the first report of C-dots with persistent RTP.
Tao, S. et al. Design of metal-free polymer carbon dots: a new class of room-temperature phosphorescent materials. Angew. Chem. Int. Ed. 57, 2393–2398 (2018).
Jiang, K. et al. Triple-mode emission of carbon dots: applications for advanced anti-counterfeiting. Angew. Chem. Int. Ed. 55, 7231–7235 (2016).
Chen, Y. et al. Room temperature phosphorescence from moisture-resistant and oxygen-barred carbon dot aggregates. J. Mater. Chem. C 5, 6243–6250 (2017).
Jiang, K., Wang, Y., Gao, X., Cai, C. & Lin, H. Facile, quick, and gram-scale synthesis of ultralong-lifetime room-temperature-phosphorescent carbon dots by microwave irradiation. Angew. Chem. Int. Ed. 57, 6216–6220 (2018).
Li, Q. et al. Induction of long-lived room temperature phosphorescence of carbon dots by water in hydrogen-bonded matrices. Nat. Commun. 9, 734 (2018).
Li, Q. et al. Efficient room-temperature phosphorescence from nitrogen-doped carbon dots in composite matrices. Chem. Mater. 28, 8221–8227 (2016).
Long, P. et al. Self-protective room-temperature phosphorescence of fluorine and nitrogen codoped carbon dots. Adv. Funct. Mater. 28, 1800791 (2018).
Zhu, J. et al. Spectrally tunable solid state fluorescence and room-temperature phosphorescence of carbon dots synthesized via seeded growth method. Adv. Opt. Mater. 7, 1801599 (2019).
Lin, C., Zhuang, Y., Li, W., Zhou, T.-L. & Xie, R.-J. Blue, green, and red full-color ultralong afterglow in nitrogen-doped carbon dots. Nanoscale 11, 6584–6590 (2019).
Zhou, Q. et al. Clustering-triggered emission of nonconjugated polyacrylonitrile. Small 12, 6586–6592 (2016).
Chen, X. et al. Synthesis, clustering-triggered emission, explosive detection and cell imaging of nonaromatic polyurethanes. Mol. Syst. Des. Eng. 3, 364–375 (2018).
Dou, X. et al. Clustering-triggered emission and persistent room temperature phosphorescence of sodium alginate. Biomacromolecules 19, 2014–2022 (2018).
Fang, M. et al. Unexpected room-temperature phosphorescence from a non-aromatic, low molecular weight, pure organic molecule through the intermolecular hydrogen bond. Mater. Chem. Front. 2, 2124–2129 (2018).
Zhou, Q. et al. Emission mechanism understanding and tunable persistent room temperature phosphorescence of amorphous nonaromatic polymers. Mater. Chem. Front. 3, 257–264 (2019).
Gong, Y. et al. Room temperature phosphorescence from natural products: Crystallization matters. Sci. China Chem. 56, 1178–1182 (2013).
Chen, X. et al. Prevalent intrinsic emission from nonaromatic amino acids and poly (amino acids). Sci. China Chem. 61, 351–359 (2018).
Du, L.-L. et al. Clustering-triggered emission of cellulose and its derivatives. Chin. J. Polym. Sci. 37, 409–415 (2019).
Zhang, H. et al. Clusterization-triggered emission: uncommon luminescence from common materials. Mater. Today 32, 275–292 (2020).
Hirata, S. Roles of localized electronic structures caused by π degeneracy due to highly symmetric heavy atom-free conjugated molecular crystals leading to efficient persistent room-temperature phosphorescence. Adv. Sci. 6, 1900410 (2019).
Hirata, S. Ultralong-lived room temperature triplet excitons: molecular persistent room temperature phosphorescence and nonlinear optical characteristics with continuous irradiation. J. Mater. Chem. C 6, 11785–11794 (2018).
Hirata, S. & Vacha, M. Large reverse saturable absorption at the sunlight power level using the ultralong lifetime of triplet excitons. J. Phys. Chem. Lett. 8, 3683–3689 (2017).
Wilson, J. S. et al. The energy gap law for triplet states in Pt-containing conjugated polymers and monomers. J. Am. Chem. Soc. 123, 9412–9417 (2001).
Tian, S. et al. Utilizing d–pπ bonds for ultralong organic phosphorescence. Angew. Chem. Int. Ed. 58, 6645–6649 (2019).
Han, J. et al. Small-molecule-doped organic crystals with long-persistent luminescence. Adv. Funct. Mater. 29, 1902503 (2019).
He, Z. et al. White light emission from a single organic molecule with dual phosphorescence at room temperature. Nat. Commun. 8, 416 (2017).
Zhang, X. et al. Ultralong UV/mechano-excited room temperature phosphorescence from purely organic cluster excitons. Nat. Commun. 10, 5161 (2019).
Li, Y., Gecevicius, M. & Qiu, J. Long persistent phosphors—from fundamentals to applications. Chem. Soc. Rev. 45, 2090–2136 (2016).
Kabe, R., Notsuka, N., Yoshida, K. & Adachi, C. Afterglow organic light-emitting diode. Adv. Mater. 28, 655–660 (2016).
Yuan, T. et al. Fluorescence–phosphorescence dual emissive carbon nitride quantum dots show 25% white emission efficiency enabling single-component WLEDs. Chem. Sci. 10, 9801–9806 (2019).
Daly, M. L., Kerr, C., DeRosa, C. A. & Fraser, C. L. Meta-alkoxy-substituted difluoroboron dibenzoylmethane complexes as environment-sensitive materials. ACS Appl. Mater. Interfaces 9, 32008–32017 (2017).
Tomkeviciene, A. et al. Bipolar thianthrene derivatives exhibiting room temperature phosphorescence for oxygen sensing. Dyes Pigm. 170, 107605 (2019).
Villa, M. et al. Bright phosphorescence of all-organic chromophores confined within water-soluble silica nanoparticles. J. Phys. Chem. C 123, 29884–29890 (2019).
Xu, J. et al. Reversible switching between phosphorescence and fluorescence in a unimolecular system controlled by external stimuli. Chem. Eur. J. 24, 12773–12778 (2018).
Katsurada, Y., Hirata, S., Totani, K., Watanabe, T. & Vacha, M. Photoreversible on–off recording of persistent room-temperature phosphorescence. Adv. Opt. Mater. 3, 1726–1737 (2015).
Xu, W. et al. Self-stabilized amorphous organic materials with room-temperature phosphorescence. Angew. Chem. Int. Ed. 58, 16018–16022 (2019).
Wang, X.-F. et al. Pure organic room temperature phosphorescence from excited dimers in self-assembled nanoparticles under visible and near-infrared irradiation in water. J. Am. Chem. Soc. 141, 5045–5050 (2019).
Pfister, A., Zhang, G., Zareno, J., Horwitz, A. F. & Fraser, C. L. Boron polylactide nanoparticles exhibiting fluorescence and phosphorescence in aqueous medium. ACS Nano 2, 1252–1258 (2008).
Chen, C. & Liu, B. Enhancing the performance of pure organic room-temperature phosphorescent luminophores. Nat. Commun. 10, 2111 (2019).
Fateminia, S. A. et al. Organic nanocrystals with bright red persistent room-temperature phosphorescence for biological applications. Angew. Chem. Int. Ed. 56, 12160–12164 (2017).
Yang, J. et al. The odd–even effect of alkyl chain in organic room temperature phosphorescence luminogens and the corresponding in vivo imaging. Mater. Chem. Front. 3, 1391–1397 (2019).
Nicol, A. et al. Ultrafast delivery of aggregation-induced emission nanoparticles and pure organic phosphorescent nanocrystals by saponin encapsulation. J. Am. Chem. Soc. 139, 14792–14799 (2017).
Zhang, G., Palmer, G. M., Dewhirst, M. W. & Fraser, C. L. A dual-emissive-materials design concept enables tumour hypoxia imaging. Nat. Mater. 8, 747–751 (2009). This work demonstrated the use of pure organic polymer room-temperature-phosphorescent materials for tumour hypoxia imaging.
Kersey, F. R., Zhang, G., Palmer, G. M., Dewhirst, M. W. & Fraser, C. L. Stereocomplexed poly(lactic acid)–poly(ethylene glycol) nanoparticles with dual-emissive boron dyes for tumor accumulation. ACS Nano 4, 4989–4996 (2010).
DeRosa, C. A. et al. Tailoring oxygen sensitivity with halide substitution in difluoroboron dibenzoylmethane polylactide materials. ACS Appl. Mater. Interfaces 7, 23633–23643 (2015).
DeRosa, C. A. et al. Oxygen sensing difluoroboron dinaphthoylmethane polylactide. Macromolecules 48, 2967–2977 (2015).
Zhen, X. et al. Ultralong phosphorescence of water-soluble organic nanoparticles for in vivo afterglow imaging. Adv. Mater. 29, 1606665 (2017).
He, Z. et al. Achieving persistent, efficient, and robust room-temperature phosphorescence from pure organics for versatile applications. Adv. Mater. 31, 1807222 (2019).
Ma, H. et al. Hydrogen bonding-induced morphology dependence of long-lived organic room-temperature phosphorescence: a computational study. J. Phys. Chem. Lett. 10, 6948–6954 (2019).
Koch, M. et al. Metal-free triplet phosphors with high emission efficiency and high tunability. Angew. Chem. Int. Ed. 53, 6378–6382 (2014).
Wang, T. et al. Aggregation-induced dual-phosphorescence from organic molecules for nondoped light-emitting diodes. Adv. Mater. 31, 1904273 (2019).
Itoh, T. Fluorescence and phosphorescence from higher excited states of organic molecules. Chem. Rev. 112, 4541–4568 (2012).
Wang, Q. et al. Reevaluating the protein emission: remarkable visible luminescence and emissive mechanism. Angew. Chem. Int. Ed. 58, 12667–12673 (2019).
Lin, Z., Kabe, R., Nishimura, N., Jinnai, K. & Adachi, C. Organic long-persistent luminescence from a flexible and transparent doped polymer. Adv. Mater. 30, 1803713 (2018).
Yang, J. et al. Elucidating the excited state of mechanoluminescence in organic luminogens with room-temperature phosphorescence. Angew. Chem. Int. Ed. 129, 15501–15505 (2017).
Yang, J. et al. AIEgen with fluorescence–phosphorescence dual mechanoluminescence at room temperature. Angew. Chem. Int. Ed. 56, 880–884 (2017).
Li, J. A. et al. Transient and persistent room-temperature mechanoluminescence from a white-light-emitting AIEgen with tricolor emission switching triggered by light. Angew. Chem. Int. Ed. 130, 6559–6563 (2018).
Su, Y. et al. Excitation-dependent long-life luminescent polymeric systems under ambient conditions. Angew. Chem. Int. Ed. 59, 9967–9971 (2020).
Gu, L. et al. Colour-tunable ultra-long organic phosphorescence of a single-component molecular crystal. Nat. Photon. 13, 406–411 (2019).
Narushima, K., Kiyota, Y., Mori, T., Hirata, S. & Vacha, M. Suppressed triplet exciton diffusion due to small orbital overlap as a key design factor for ultralong-lived room-temperature phosphorescence in molecular crystals. Adv. Mater. 31, 1807268 (2019).
Clapp, D. B. The phosphorescence of tetraphenylmethane and certain related substances. J. Am. Chem. Soc. 61, 523–524 (1939).
Xue, P. et al. Correction: Bright persistent luminescence from pure organic molecules through a moderate intermolecular heavy atom effect. Chem. Sci. 8, 6691 (2017).
The authors acknowledge financial support by the National Science Foundation of China (21975061, 21788102, 51703042), the Natural Scientific Research Innovation Foundation in Harbin Institute of Technology (HIT.NSRIF.2020062), the National Science Foundation of Guangdong Province (2019A1515011050), the Science and Technology Plan of Shenzhen (JCYJ20170811155015918), the Research Grants Council of Hong Kong (C6009-17G and A-HKUST605/16) and the Innovation and Technology Commission (ITC-CNERC14SC01). The authors are grateful to Professor Qian Peng and Professor Huili Ma for helpful discussions.
The authors declare no competing interests.
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
About this article
Cite this article
Zhao, W., He, Z. & Tang, B.Z. Room-temperature phosphorescence from organic aggregates. Nat Rev Mater (2020). https://doi.org/10.1038/s41578-020-0223-z