Perovskite light-emitting diodes are promising for next-generation lighting and displays because of their high colour purity and performance1. Although the management of singlet and triplet excitons is fundamental to the design of efficient organic light-emitting diodes, the nature of how excitons affect performance is still not clear in perovskite2,3,4 and quasi-two-dimensional (2D) perovskite-based devices5,6,7,8,9. Here, we show that triplet excitons are key to efficient emission in green quasi-2D perovskite devices and that quenching of triplets by the organic cation is a major loss path. Employing an organic cation with a high triplet energy level (phenylethylammonium) in a quasi-2D perovskite based on formamidinium lead bromide yields efficient harvesting of triplets. Furthermore, we show that upconversion of triplets to singlets can occur, making 100% harvesting of electrically generated excitons potentially possible. The external quantum and current efficiencies of our green (527 nm) devices reached 12.4% and 52.1 cd A−1, respectively.
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The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.
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This work was supported by the Japan Science and Technology Agency (JST), ERATO, Adachi Molecular Exciton Engineering Project under JST ERATO grant no. JPMJER1305, Japan, and the International Institute for Carbon Neutral Energy Research (WPI-I2CNER) sponsored by the Ministry of Education, Culture, Sports, Science and Technology (MEXT), and The Canon Foundation. C.Q. acknowledges support from funding by the Changchun Institute of Applied Chemistry (CIAC). We thank Pohang Accelerator Laboratory (PAL) for giving us the opportunity to perform the GIWAXS measurements and MEST and POSTECH for supporting these experiments, H. Ahn for adjustments and help, and other colleagues from the 9A USAXS beamline for assistance. Part of this work at Kyoto was supported by JST-CREST (grant no. JPMJCR16N3). This research was supported in part by the CNRS (PICS N8 8085), France.
The authors declare no competing interests.
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Qin, C., Matsushima, T., Potscavage, W.J. et al. Triplet management for efficient perovskite light-emitting diodes. Nat. Photonics 14, 70–75 (2020). https://doi.org/10.1038/s41566-019-0545-9