Li Na Quan, University of Toronto
Reduced Dimensionality Perovskite for Photovoltaics and Light-Emitting Diodes
Written by Xiwen Gong
As an emerging class of semiconducting materials, organic-inorganic hybrid perovskites have so-far led to great advances in the performance of solution-processed optoelectronic devices. However, many as-formed lead halide perovskite thin films lack chemical and structural stability, leading to rapid degradation in the presence of moisture. Therefore, for perovskite materials to make an impact in light emission field, it is necessary to overcome their free-carrier nature of electrons and holes in perovskites at room temperature.
Li Na Quan from the University of Toronto investigated a novel material platform of mixed organic, dimensionally-tunable quasi-two-dimensional (2D) perovskite thin films that can be used to bridge the gap between 2D and 3D materials. Quasi-2D perovskite films exhibit improved stability due to the increased formation energy, while retaining the high performance characteristics of MAPbI3 perovskites. As a result, they achieved an improved stability perovskite solar cell power conversion efficiency around 18%.
As follow-up work with quai-2D perovskites, they studied a mixed materials perovskites that was composed of different quantum-sized, tuned grains. This resulted in an enhanced photoluminescence quantum yield and high performance of light-emitting diode under the 750 nm near-infrared operation conditions. They have explained the charge carrier dynamics of the materials from the ultra-fast transient absorption study.
In this way, they obtained a view of the charge transfer. The results indicate that the multiphase perovskite materials channel energy across an inhomogeneous energy landscape and thus concentrate carriers on smaller bandgap emitters.