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http://dx.doi.org/10.3807/COPP.2018.2.6.514

Direct Measurement of Diffusion Length in Mixed Lead-halide Perovskite Films Using Scanning Photocurrent Microscopy  

Kim, Ahram (Department of Physics and Department of Energy Systems Research, Ajou University)
Son, Byung Hee (Department of Physics and Department of Energy Systems Research, Ajou University)
Kim, Hwan Sik (Department of Physics and Department of Energy Systems Research, Ajou University)
Ahn, Yeong Hwan (Department of Physics and Department of Energy Systems Research, Ajou University)
Publication Information
Current Optics and Photonics / v.2, no.6, 2018 , pp. 514-518 More about this Journal
Abstract
Carrier diffusion length in the light-sensitive material is one of the key elements in improving the light-current conversion efficiency of solar-cell devices. In this paper, we measured the carrier diffusion length in lead-halide perovskite ($MAPbI_3$) and mixed lead-halide ($MAPbI_{3-x}Cl_x$) perovskite devices using scanning photocurrent microscopy (SPCM). The SPCM signal decreased as we moved the focused laser spot away from the metal contact. By fitting the data with a simple exponential curve, we extracted the carrier diffusion length of each perovskite film. Importantly, the diffusion length of the mixed-halide perovskite was higher than that of the halide perovskite film by a factor of 3 to 6; this is consistent with the general expectation that the carrier mobility will be higher in the case of the mixed lead-halide perovskites. Finally, the diffusion length was investigated as a function of applied bias for both samples, and analyzed successfully in terms of the drift-diffusion model.
Keywords
Perovskites; Diffusion length; Scanning photocurrent microscopy;
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