High Excitation Intensity Opens a New Trapping Channel in Organic - Inorganic Hybrid Perovskite Nanoparticles

0469197 - ÚFP 2017 RIV US eng J - Journal Article
Zheng, K. - Žídek, Karel - Abdellah, M. - Chen, J.S. - Chábera, P. - Zhang, W. - Al-Marri, M.J. - Pullerits, T.
High Excitation Intensity Opens a New Trapping Channel in Organic - Inorganic Hybrid Perovskite Nanoparticles.
ACS ENERGY LETTERS. Roč. 1, č. 6 (2016), s. 1154-1161. ISSN 2380-8195. E-ISSN 2380-8195
Institutional support: RVO:61389021
Keywords : LEAD HALIDE PEROVSKITES * QUANTUM DOTS * NANOCRYSTALS
OECD category: Condensed matter physics (including formerly solid state physics, supercond.)

We investigated the excited-state dynamics of CH3NH3PbBr3 perovskite nanoparticles (NPs) and bulk crystals under various excitation intensity regimes using transient absorption spectroscopy. We confirmed the sub-band gap hole trap states with optical transition to the conduction band in both samples. In bulk crystals, the excited-state dynamics is independent of pump intensity. However, in NPs, pronounced intensity dependence appears. At low intensities, the hole trap states do not affect the excited-state dynamics due to the potential barrier between the photogenerated holes and the surface trap states. When the excitation density is much higher than one per NP, charge accumulation makes hot holes overcome the barrier and get trapped with electrons long living in the conduction band (≫10 ns). This explains the high emissive properties of such NPs despite the existence of surface traps. However, in the application of emitting devices requiring high excitation intensity, the surface trapping becomes significant.
Permanent Link: http://hdl.handle.net/11104/0267025