Perovskite solar cells (PSCs) have emerged as an attractive photovoltaic technology thanks to their outstanding power conversion efficiency (PCE). Further improvement in the device efficiency is limited by the recombination of the charge carriers in the perovskite layer even when employing heterojunction-based architectures. Here, we propose and demonstrate a p-type perovskite/n-type perovskite homojunction whose built-in electric field promotes oriented transport of the photo-induced carriers, thus reducing carrier recombination losses. By controlling the stoichiometry of the perovskite precursors, we are able to induce n-type or p-type doping. We integrate the homojunction structure in a planar PSC combining a thermally evaporated p-type perovskite layer on a solution-processed n-type perovskite layer. The PSC with a MAPbI3 homojunction achieves a PCE of 20.80% (20.5% certified PCE), whereas the PSC based on a FA0.15MA0.85PbI3 homojunction delivers a PCE of 21.38%. We demonstrate that the homojunction structure is an effective approach, beyond existing planar heterojunction PSCs, to achieve highly efficient PSCs with reduced carrier recombination losses.
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The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.
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This work is supported partially by the National Natural Science Foundation of China (grant no. 51772096), the Natural Science Foundation of Beijing Municipality (L172036), Joint Funds of the Equipment Pre-Research and Ministry of Education (6141A020225), the Par-Eu Scholars Program, the Science and Technology Beijing 100 Leading Talent Training Project, the Beijing Municipal Science and Technology Project (Z161100002616039), the Fundamental Research Funds for the Central Universities (2016JQ01 and 2017ZZD02) and the NCEPU `Double First-Class' Graduate Talent Cultivation Program. We thank Z. Cheng, R. Xu and Z. Liu for KPFM measurements and analysis, and X. Han and Z. Li for high-resolution TEM measurements. P.C. acknowledges the scholarship from the China Scholarship Council and thanks G. Cao for fruitful discussions.
The authors declare no competing interests.
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Cui, P., Wei, D., Ji, J. et al. Planar p–n homojunction perovskite solar cells with efficiency exceeding 21.3%. Nat Energy 4, 150–159 (2019). https://doi.org/10.1038/s41560-018-0324-8
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