Electron-hole diffusion lengths exceeding 1 micrometer in an organometal trihalide perovskite absorber.

Stranks, Samuel D; Eperon, Giles E; Grancini, Giulia; Menelaou, Christopher; Alcocer, Marcelo J P; Leijtens, Tomas; Herz, Laura M; Petrozza, Annamaria et al. · Science · 2013

basic_science · Level V

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Abstract

Organic-inorganic perovskites have shown promise as high-performance absorbers in solar cells, first as a coating on a mesoporous metal oxide scaffold and more recently as a solid layer in planar heterojunction architectures. Here, we report transient absorption and photoluminescence-quenching measurements to determine the electron-hole diffusion lengths, diffusion constants, and lifetimes in mixed halide (CH3NH3PbI(3-x)Cl(x)) and triiodide (CH3NH3PbI3) perovskite absorbers. We found that the diffusion lengths are greater than 1 micrometer in the mixed halide perovskite, which is an order of magnitude greater than the absorption depth. In contrast, the triiodide absorber has electron-hole diffusion lengths of ~100 nanometers. These results justify the high efficiency of planar heterojunction perovskite solar cells and identify a critical parameter to optimize for future perovskite absorber development.