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Two‐Photon Up‐Conversion Photoluminescence Realized through Spatially Extended Gap States in Quasi‐2D Perovskite Films
Author(s) -
Zhu Xixiang,
Xu Hengxing,
Liu Yongtao,
Zhang Jia,
Wang Miaosheng,
Ivanov Ilia N.,
Ovchinnikova Olga S.,
Hu Bin
Publication year - 2019
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.201901240
Subject(s) - photoexcitation , photoluminescence , energy conversion efficiency , materials science , excitation , polarization (electrochemistry) , perovskite (structure) , photon , band gap , optoelectronics , condensed matter physics , optics , physics , chemistry , quantum mechanics , crystallography
A new approach to generate a two‐photon up‐conversion photoluminescence (PL) by directly exciting the gap states with continuous‐wave (CW) infrared photoexcitation in solution‐processing quasi‐2D perovskite films [(PEA) 2 (MA) 4 Pb 5 Br 16 with n = 5] is reported. Specifically, a visible PL peaked at 520 nm is observed with the quadratic power dependence by exciting the gap states with CW 980 nm laser excitation, indicating a two‐photon up‐conversion PL occurring in quasi‐2D perovskite films. Decreasing the gap states by reducing the n value leads to a dramatic decrease in the two‐photon up‐conversion PL signal. This confirms that the gap states are indeed responsible for generating the two‐photon up‐conversion PL in quasi‐2D perovskites. Furthermore, mechanical scratching indicates that the different‐ n ‐value nanoplates are essentially uniformly formed in the quasi‐2D perovskite films toward generating multi‐photon up‐conversion light emission. More importantly, the two‐photon up‐conversion PL is found to be sensitive to an external magnetic field, indicating that the gap states are essentially formed as spatially extended states ready for multi‐photon excitation. Polarization‐dependent up‐conversion PL studies reveal that the gap states experience the orbit–orbit interaction through Coulomb polarization to form spatially extended states toward developing multi‐photon up‐conversion light emission in quasi‐2D perovskites.