The remarkable properties of metal halide perovskites arising from their impressive charge carrier diffusion lengths have led to rapid advances in solution-processed optoelectronics. Unfortunately, diffusion lengths reported in perovskite single crystals have ranged widely – from 3 μm to 3 mm – for ostensibly similar materials. Here we report a contactless method to measure the carrier mobility and further extract the diffusion length: our approach avoids both the effects of contact resistance and those of high electric field. We vary the density of quenchers – epitaxially included within perovskite single crystals – and report the dependence of excited state lifetime in the perovskite on inter-quencher spacing. Our results are repeatable and self-consistent (i.e. they agree on diffusion length for many different quencher concentrations) to within ± 6%. Using this method, we obtain a diffusion length in metal-halide perovskites of 2.6 μm ± 0.1 μm.
Gong, X., Huang, Z., Sabatini, R., Tan, C-S., Bappi, G., Walters, G., Proppe, A., Saidaminov, M. I., Voznyy, O., Kelley, S. O., & Sargent, E. H. (2019). Contactless measurements of photocarrier transport properties in perovskite single crystals. Nature Communications, 10(1), . https://doi.org/10.1038/s41467-019-09538-7