期刊
JOURNAL OF PHYSICAL CHEMISTRY C
卷 122, 期 2, 页码 1119-1124出版社
AMER CHEMICAL SOC
DOI: 10.1021/acs.jpcc.7b11503
关键词
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资金
- Department of Science AMP
- Technology, India [DST/TM/SERI/FR/186(G)]
- Department of Science and Technology (DST), India
- Council of Scientific and Industrial Research (CSIR), India
The photoluminescence (PL) decay of hybrid halide perovskite single crystals (MAPbX(3), MA = CH3NH3+, Pb = Pb2+, X = Br-, and I-) is measured over 4 orders of magnitude in intensity over the time scales of 100s of nanoseconds to a few microseconds. This long PL decay is non-exponential, suggesting the presence of a distribution of carrier relaxation times. Spectro-temporal studies show that the emission peak red-shifts with increasing time. The physics of this problem is closely related to donor-acceptor pair recombination in crystalline semiconductors and recombination in a-Si:H. Based on these models, we present a simple model to account for the recombination dynamics in the perovskite systems. This model also accounts for the fluence dependence of the recombination kinetics. In this model, a fraction of the photogenerated electrons and holes are trapped in localized states. The electrons tunnel to the hole sites for recombination. The broad distribution of lifetimes is a consequence of the fact that the tunneling probability is very sensitive to the separation of electron-hole pairs, and PL decay dynamics is a function of excitation fluence, i.e., carrier density generated by optical excitation. The red-shift arises from the fact that holes and electrons are trapped at different energies.
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