Triplet management for efficient perovskite light-emitting diodes

• Published in: Nature photonics Vol. 14; no. 2; pp. 70 - 75
• Main Authors: Qin, Chuanjiang, Matsushima, Toshinori, Potscavage, William J., Sandanayaka, Atula S. D., Leyden, Matthew R., Bencheikh, Fatima, Goushi, Kenichi, Mathevet, Fabrice, Heinrich, Benoît, Yumoto, Go, Kanemitsu, Yoshihiko, Adachi, Chihaya
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.02.2020; Nature Publishing Group
• Subjects: 639/301/1019/1020/1091; 639/624/1020; Applied and Technical Physics; Cations; Chemical Sciences; Energy levels; Excitons; Letter; Light emitting diodes; Organic light emitting diodes; Perovskites; Physics; Physics and Astronomy; Quantum Physics; Upconversion
• ISSN: 1749-4885; 1749-4893
• DOI: 10.1038/s41566-019-0545-9

Perovskite light-emitting diodes are promising for next-generation lighting and displays because of their high colour purity and performance 1 . 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 perovskite 2 – 4 and quasi-two-dimensional (2D) perovskite-based devices 5 – 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. Careful harvesting of triplet excitons allows the realization of efficient green-emitting quasi-2D perovskite LEDs.