The ability of energy carriers to move between atoms and molecules underlies biochemical and material function. Understanding and controlling energy flow, however, requires observing it on ultrasmall and ultrafast spatio-temporal scales, where energetic and structural roadblocks dictate the fate of energy carriers. Here, we developed a non-invasive optical scheme that leverages non-resonant interferometric scattering to track tiny changes in material polarizability created by energy carriers. We thus map evolving energy carrier distributions in four dimensions of spacetime with few-nanometre lateral precision and directly correlate them with material morphology. We visualize exciton, charge and heat transport in polyacene, silicon and perovskite semiconductors and elucidate how disorder affects energy flow in three dimensions. For example, we show that morphological boundaries in polycrystalline metal halide perovskites possess lateral- and depth-dependent resistivities, blocking lateral transport for surface but not bulk carriers. We also reveal strategies for interpreting energy transport in disordered environments that will direct the design of defect-tolerant materials for the semiconductor industry of tomorrow.
Subscribe to Journal
Get full journal access for 1 year
only $16.58 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.
García de Arquer, F. P., Armin, A., Meredith, P. & Sargent, E. H. Solution-processed semiconductors for next-generation photodetectors. Nat. Rev. Mater. 2, 16100 (2017).
Sirringhaus, H., Tessler, N. & Friend, R. Integrated optoelectronic devices based on conjugated polymers. Science 280, 1741–1744 (1998).
Scholes, G. D. & Rumbles, G. Excitons in nanoscale systems. Nat. Mater. 5, 683–696 (2006).
Brenner, T. M. et al. Are mobilities in hybrid organic-inorganic halide perovskites actually ‘high’? J. Phys. Chem. Lett. 6, 4754–4757 (2015).
Akselrod, G. M. et al. Visualization of exciton transport in ordered and disordered molecular solids. Nat. Commun. 5, 3646 (2014).
Penwell, S. B., Ginsberg, L. D. S., Noriega, R. & Ginsberg, N. S. Resolving ultrafast exciton migration in organic solids at the nanoscale. Nat. Mater. 16, 1136–1142 (2017).
Kulig, M. et al. Exciton diffusion and halo effects in monolayer semiconductors. Phys. Rev. Lett. 120, 207401 (2018).
Seo, M. A. et al. Mapping carrier diffusion in single silicon core-shell nanowires with ultrafast optical microscopy. Nano Lett. 12, 6334–6338 (2012).
Gabriel, M. M. et al. Direct imaging of free carrier and trap carrier motion in silicon nanowires by spatially-separated femtosecond pump–probe microscopy. Nano Lett. 13, 1336–1340 (2013).
Guo, Z., Manser, J. S., Wan, Y., Kamat, P. V. & Huang, L. Spatial and temporal imaging of long-range charge transport in perovskite thin films by ultrafast microscopy. Nat. Commun. 6, 7471–7479 (2015).
Rozenman, G. G., Akulov, K., Golombek, A. & Schwartz, T. Long-range transport of organic exciton-polaritons revealed by ultrafast microscopy. ACS Photon. 5, 105–110 (2018).
Najafi, E., Scarborough, T. D., Tang, J. & Zewail, A. Four-dimensional imaging of carrier interface dynamics in p-n junctions. Science 347, 164–167 (2015).
Plakhotnik, T. & Palm, V. Interferometric signatures of single molecules. Phys. Rev. Lett. 87, 183602-1–183602-4 (2001).
Wolpert, C. et al. Transient reflection: a versatile technique for ultrafast spectroscopy of a single quantum dot in complex environments. Nano Lett. 12, 453–457 (2012).
Karrai, K. & Warburton, R. J. Optical transmission and reflection spectroscopy of single quantum dots. Superlattice. Microst 33, 311–337 (2003).
Amos, L. A. & Amos, W. B. The bending of sliding microtubules imaged by confocal light microscopy and negative stain electron microscopy. J. Cell Sci. 1991, 95–101 (1991).
Lindfors, K., Kalkbrenner, T., Stoller, P. & Sandoghdar, V. Detection and spectroscopy of gold nanoparticles using supercontinuum white light confocal microscopy. Phys. Rev. Lett. 93, 037401 (2004).
Jacobsen, V., Stoller, P., Brunner, C., Vogel, V. & Sandoghdar, V. Interferometric optical detection and tracking of very small gold nanoparticles at a water-glass interface. Opt. Express 14, 405–414 (2006).
Young, G. et al. Quantitative mass imaging of single biological macromolecules. Science 360, 423–427 (2018).
Ortega-Arroyo, J. & Kukura, P. Interferometric scattering microscopy (iSCAT): new frontiers in ultrafast and ultrasensitive optical microscopy. Phys. Chem. Chem. Phys. 14, 15625–15636 (2012).
Ignatovich, F. V. & Novotny, L. Real-time and background-free detection of nanoscale particles. Phys. Rev. Lett. 96, 1–4 (2006).
Berciaud, S., Cognet, L., Blab, G. A. & Lounis, B. Photothermal heterodyne imaging of individual nonfluorescent nanoclusters and nanocrystals. Phys. Rev. Lett. 93, 257402 (2004).
Boyer, D., Tamarat, P., Maali, A., Lounis, B. & Orrit, M. Photothermal imaging of nanometer-sized metal particles among scatterers. Science 297, 1160–1163 (2002).
Price, M. B. et al. Hot-carrier cooling and photoinduced refractive index changes in organic–inorganic lead halide perovskites. Nat. Commun. 6, 8420 (2015).
Yang, Y. et al. Top and bottom surfaces limit carrier lifetime in lead iodide perovskite films. Nat. Energy 2, 1–7 (2017).
Sorenson, S. A., Patrow, J. G. & Dawlaty, J. M. Electronic dynamics in natural iron pyrite studied by broadband transient reflection spectroscopy. J. Phys. Chem. C. 120, 7736–7747 (2016).
Jacoboni, C., Canali, C., Otiaviani, G. & Quaranta, A. A. A review of some charge transport properties of silicon. Solid State Phys. 20, 77–89 (1977).
Shanks, H. R., Maycock, P. D., Sidles, P. H. & Danielson, G. C. Thermal conductivity of silicon from 300 to 1400 K. Phys. Rev. 130, 1743–1748 (1963).
Shi, D. et al. Low trap-state density and long carrier diffusion in organolead trihalide perovskite single crystals. Science 347, 519–522 (2015).
Hill, A. H., Smyser, K. E., Kennedy, C. L., Massaro, E. S. & Grumstrup, E. M. Screened charge carrier transport in methylammonium lead iodide perovskite thin films. J. Phys. Chem. Lett. 8, 948–953 (2017).
Anthony, J. E., Brooks, J. S., Eaton, D. L. & Parkin, S. R. Functionalized pentacene: improved electronic properties from control of solid-state order. J. Am. Chem. Soc. 123, 9482–9483 (2001).
Giri, G. et al. Tuning charge transport in solution-sheared organic semiconductors using lattice strain. Nature 480, 504–508 (2011).
Chen, J., Tee, C. K., Shtein, M., Anthony, J. & Martin, D. C. Grain-boundary-limited charge transport in solution-processed 6,13 bis(tri-isopropylsilylethynyl) pentacene thin film transistors. J. Appl. Phys. 103, 114513 (2008).
Zhu, T., Wan, Y., Guo, Z., Johnson, J. & Huang, L. Two birds with one stone: tailoring singlet fission for both triplet yield and exciton diffusion length. Adv. Mater. 7539–7547 (2016). https://doi.org/10.1002/adma.201600968
Rivnay, J. et al. Large modulation of carrier transport by grain-boundary molecular packing and microstructure in organic thin films. Nat. Mater. 8, 952–958 (2009).
Greuter, F. & Blatter, G. Electrical properties of grain boundaries in polycrystalline compound semiconductors. Semicond. Sci. Technol. 5, 111–137 (1990).
Yun, J. S. et al. Benefit of grain boundaries in organic-inorganic halide planar perovskite solar cells. J. Phys. Chem. Lett. 6, 875–880 (2015).
Reid, O. G., Yang, M., Kopidakis, N., Zhu, K. & Rumbles, G. Grain-size-limited mobility in methylammonium lead iodide perovskite thin films. ACS Energy Lett. 1, 561–565 (2016).
DeQuilettes, D. W. et al. Impact of microstructure on local carrier lifetime in perovskite solar cells. Science 348, 683–686 (2015).
DeQuilettes, D. W. et al. Tracking photoexcited carriers in hybrid perovskite semiconductors: trap-dominated spatial heterogeneity and diffusion. ACS Nano 11, 11488–11496 (2017).
Tian, W. et al. Limiting perovskite solar cell performance by heterogeneous carrier extraction. Angew. Chem. Int. Ed. 55, 13067–13071 (2016).
Ciesielski, R. et al. Grain boundaries act as solid walls for charge carrier diffusion in large crystal MAPI thin films. ACS Appl. Mater. Interf. 10, 7974–7981 (2018).
MacDonald, G. A. et al. Methylammonium lead iodide grain boundaries exhibit depth-dependent electrical properties. Energy Environ. Sci. 9, 3642–3649 (2016).
Schnedermann, C. et al. Sub-10 fs time-resolved vibronic optical microscopy. J. Phys. Chem. Lett. 7, 4854–4859 (2016).
Snaider, J. M. et al. Ultrafast imaging of carrier transport across grain boundaries in hybrid perovskite thin films. ACS Energy Lett. 3, 1402–1408 (2018).
Saliba, M., Correa-Baena, J. P., Grätzel, M., Hagfeldt, A. & Abate, A. Perovskite solar cells: from the atomic level to film quality and device performance. Angew. Chem. Int. Ed. 57, 2554–2569 (2018).
Berry, J. et al. Hybrid organic-inorganic perovskites (HOIPs): opportunities and challenges. Adv. Mater. 27, 5102–5112 (2015).
Krishnan, M., Mojarad, N., Kukura, P. & Sandoghdar, V. Geometry-induced electrostatic trapping of nanometric objects in a fluid. Nature 467, 692–695 (2010).
Baffou, G. et al. Thermal imaging of nanostructures by quantitative optical phase analysis. ACS Nano 6, 2452–2458 (2012).
Celebrano, M., Kukura, P., Renn, A. & Sandoghdar, V. Single-molecule imaging by optical absorption. Nat. Photon. 5, 95–98 (2011).
Ortega Arroyo, J., Cole, D. & Kukura, P. Interferometric scattering microscopy and its combination with single-molecule fluorescence imaging. Nat. Protoc. 11, 617–633 (2016).
This work was supported by STROBE, A National Science Foundation Science and Technology Center under grant no. DMR 1548924. The manuscript revision was also supported by the Photonics at Thermodynamic Limits Energy Frontier Research Center, funded by the US Department of Energy Office of Science Basic Energy Sciences Program, under award no. DE-SC0019140. Q.Y. and H.L.W. acknowledge National Science Foundation Graduate Research Fellowship DGE 1106400. N.S.G. acknowledges an Alfred P. Sloan Research Fellowship, a David and Lucile Packard Foundation Fellowship for Science and Engineering, and a Camille and Henry Dreyfus Teacher-Scholar Award.
The authors declare no competing interests.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Detailed description of the stroboSCAT set-up, stroboSCAT contrast mechanism, data analysis, sample preparation, current system resolution, distinguishing scattering from normal reflection, supporting experimental data, in situ spectral interferometry on MAPbI3(Cl) films, simulations of depth-dependent carrier diffusion in polycrystalline films using the finite element method, Figs. 1–24 and refs. 1–54.
About this article
Cite this article
Delor, M., Weaver, H.L., Yu, Q. et al. Imaging material functionality through three-dimensional nanoscale tracking of energy flow. Nat. Mater. (2019) doi:10.1038/s41563-019-0498-x
Ultrafast Tracking of Exciton and Charge Carrier Transport in Optoelectronic Materials on the Nanometer Scale
The Journal of Physical Chemistry Letters (2019)