Understanding the Origin of Non-Radiative Decay in Metal Halide Perovskites
ONE Lab: Samuel D. Stranks, Anna Osherov, Roberto Brenes, Farnaz Niroui, Vladimir Bulović
Collaborators: Dane W. deQuilettes, Daniel J. Graham, David S. Ginger (University of Washington), Wei Zhang, Victor M. Burlakov, Henry J. Snaith (University of Oxford)
Organic-inorganic metal halide perovskites such as CH3NH3PbI3 are generating a great deal of excitement for their potential applications in a variety of high-performance optoelectronic devices including solar cells, light-emitting diodes, photodetectors, and lasers. These applications are enabled by the favorable material properties of these perovskites, which include long charge carrier diffusion lengths, high absorption coefficients with a sharp absorption edge, and a remarkably high photoluminescence quantum efficiency (PLQE). This latter property is particularly important for approaching the highest photovoltaic device performances at the Shockley-Queisser limit, in which all non-radiative recombination is eliminated. Nevertheless, we recently reported that the PL lifetimes and intensities vary substantially between different grains even in high quality films.
In this project, we seek to understand the physical and chemical origin of the non-radiative decay and heterogeneity between grains. We use a range of tools including time-resolved confocal photoluminescence (PL) mapping, time-of-flight secondary ion mass spectrometry (ToF-SIMS) and energy-dispersive X-ray spectroscopy (EDX) to provide correlations between local photophysics and local chemistry. This important information will enable us to target methods to eliminate non-radiative decay through higher quality film fabrication and passivation post-treatments, ultimately yielding better performing devices.
Perovskite crystal structure ABX3, (b) Confocal photoluminescence map overlaid over a scanning electron microscope (SEM) image of a CH3NH3PbI3 film showing “bright” and “dark” grains