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Published on: September 8, 2017
Mixed-Halide Perovskites with Stabilized Bandgaps
Zhengguo Xiao1, Lianfeng Zhao1, Nhu L Tran1
1Department of Electrical Engineering, ‡Department of Chemistry, §Princeton Institute for the Science and Technology of Materials, and ∥Andlinger Center for Energy and the Environment, Princeton University , Princeton, New Jersey 08544, United States.
Abstract:
One merit of organic-inorganic hybrid perovskites is their tunable bandgap by adjusting the halide stoichiometry, an aspect critical to their application in tandem solar cells, wavelength-tunable light emitting diodes (LEDs), and lasers. However, the phase separation of mixed-halide perovskites caused by light or applied bias results in undesirable recombination at iodide-rich domains, meaning open-circuit voltage (VOC) pinning in solar cells and infrared emission in LEDs. Here, we report an approach to suppress halide redistribution by self-assembled long-chain organic ammonium capping layers at nanometer-sized grain surfaces. Using the stable mixed-halide perovskite films, we are able to fabricate efficient and wavelength-tunable perovskite LEDs from infrared to green with high external quantum efficiencies of up to 5%, as well as linearly tuned VOC from 1.05 to 1.45 V in solar cells.
