Improvement in quantum yield by suppression of trions in room temperature synthesized CsPbBr3 perovskite quantum dots for backlight displays

Kashyap Dave; Zhen Bao; Satoshi Nakahara; Keiichi Ohara; Sojiro Masada; Hirokazu Tahara; Yoshihiko Kanemitsu; Ru-Shi Liu

doi:10.1039/c9nr09056h

Improvement in quantum yield by suppression of trions in room temperature synthesized CsPbBr₃ perovskite quantum dots for backlight displays

Nanoscale. 2020 Feb 14;12(6):3820-3826. doi: 10.1039/c9nr09056h. Epub 2020 Jan 29.

Authors

Kashyap Dave¹, Zhen Bao², Satoshi Nakahara³, Keiichi Ohara³, Sojiro Masada³, Hirokazu Tahara³, Yoshihiko Kanemitsu³, Ru-Shi Liu⁴

Affiliations

¹ Department of Chemistry and Advanced Research Center of Green Materials Science and Technology, National Taiwan University, Taipei 106, Taiwan. rsliu@ntu.edu.tw and Nanoscience and Technology Program, Taiwan International Graduate Program, Academia Sinica and National Taiwan University, Taipei 115, Taiwan.
² Department of Chemistry and Advanced Research Center of Green Materials Science and Technology, National Taiwan University, Taipei 106, Taiwan. rsliu@ntu.edu.tw.
³ Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan. kanemitu@scl.kyoto-u.ac.jp.
⁴ Department of Chemistry and Advanced Research Center of Green Materials Science and Technology, National Taiwan University, Taipei 106, Taiwan. rsliu@ntu.edu.tw and Department of Mechanical Engineering and Graduate Institute of Manufacturing Technology, National Taipei University of Technology, Taipei 106, Taiwan.

PMID: 31995086
DOI: 10.1039/c9nr09056h

Abstract

Surface defects and synthesis methods play important roles in the photoluminescence quantum yield (PLQY), stability, and the device performance of lead halide perovskite quantum dots (PQDs). In this study, we report a quadruple-ligand (tri-n-octylphosphine, didodecyldimethylammonium bromide, tetraoctylammonium bromide, and oleic acid) assisted room-temperature method for synthesizing CsPbBr₃ QDs (RT-CsPbBr₃) with an absolute PLQY of 83%. X-ray photoelectron spectroscopy confirms the high completeness of the Pb-Br octahedron through the absence of lead ions and presence of more bromide ions on the surface of RT-CsPbBr₃ QDs. The exciton dynamics of RT-CsPbBr₃ QDs is studied by using femtosecond transient absorption, time-resolved PL, and single-dot spectroscopy, which provide strong evidence of the suppression of trion formation compared with the hot injection-synthesized CsPbBr₃ (HI-CsPbBr₃) QDs. The white light-emitting diode (LED) fabricated with RT-CsPbBr₃ PQDs and a K₂SiF₆:Mn⁴⁺ phosphor for backlight applications achieved a wide color gamut of 124% of the National Television System Committee (NTSC) standard.