Long-Range Balanced Electron- and Hole-Transport Lengths in Organic-Inorganic CH ₃ NH ₃ PbI ₃

Abstract

Unrestricted Travel in Solar Cells In the past 2 years, organolead halide perovskites have emerged as a promising class of light-harvesting media in experimental solar cells, but the physical basis for their efficiency has been unclear (see the Perspective by Hodes ). Two studies now show, using a variety of time-resolved absorption and emission spectroscopic techniques, that these materials manifest relatively long diffusion paths for charge carriers energized by light absorption. Xing et al. (p. 344 ) independently assessed (negative) electron and (positive) hole diffusion lengths and found them well-matched to one another to the ~100-nanometer optical absorption depth. Stranks et al. (p. 341 ) uncovered a 10-fold greater diffusion length in a chloride-doped material, which correlates with the material's particularly efficient overall performance. Both studies highlight effective carrier diffusion as a fruitful parameter for further optimization.

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Affiliated Institutions

• École Polytechnique Fédérale de Lausanne CH
• Singapore-MIT Alliance for Research and Technology SG
• Nanyang Technological University SG
• RWTH Aachen University DE

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