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Lead Selenide Colloidal Quantum Dot Solar Cells Achieving High Open-Circuit Voltage with One-Step Deposition Strategy

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journal contribution
posted on 15.06.2018 by Yaohong Zhang, Guohua Wu, Chao Ding, Feng Liu, Yingfang Yao, Yong Zhou, Congping Wu, Naoki Nakazawa, Qingxun Huang, Taro Toyoda, Ruixiang Wang, Shuzi Hayase, Zhigang Zou, Qing Shen
Lead selenide (PbSe) colloidal quantum dots (CQDs) are considered to be a strong candidate for high-efficiency colloidal quantum dot solar cells (CQDSCs) due to its efficient multiple exciton generation. However, currently, even the best PbSe CQDSCs can only display open-circuit voltage (Voc) about 0.530 V. Here, we introduce a solution-phase ligand exchange method to prepare PbI2-capped PbSe (PbSe-PbI2) CQD inks, and for the first time, the absorber layer of PbSe CQDSCs was deposited in one step by using this PbSe-PbI2 CQD inks. One-step-deposited PbSe CQDs absorber layer exhibits fast charge transfer rate, reduced energy funneling, and low trap assisted recombination. The champion large-area (active area is 0.35 cm2) PbSe CQDSCs fabricated with one-step PbSe CQDs achieve a power conversion efficiency (PCE) of 6.0% and a Voc of 0.616 V, which is the highest Voc among PbSe CQDSCs reported to date.