Acetate Salts as Nonhalogen Additives To Improve Perovskite Film Morphology for High-Efficiency Solar Cells

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• 作者：Qiliang Wu ; Pengcheng Zhou ; Weiran Zhou ; Xiangfeng Wei ; Tao Chen ; Shangfeng Yang
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2016
• 出版时间：June 22, 2016
• 年：2016
• 卷：8
• 期：24
• 页码：15333-15340
• 全文大小：463K
• 年卷期：0
• ISSN：1944-8252

文摘

A two-step method has been popularly adopted to fabricate a perovskite film of planar heterojunction organo-lead halide perovskite solar cells (PSCs). However, this method often generates uncontrollable film morphology with poor coverage. Herein, we report a facile method to improve perovskite film morphology by incorporating a small amount of acetate (CH₃COO^–, Ac^–) salts (NH₄Ac, NaAc) as nonhalogen additives in CH₃NH₃I solution used for immersing PbI₂ film, resulting in improved CH₃NH₃PbI₃ film morphology. Under the optimized NH₄Ac additive concentration of 10 wt %, the best power conversion efficiency (PCE) reaches 17.02%, which is enhanced by ∼23.2% relative to that of the pristine device without additive, whereas the NaAc additive does not lead to an efficiency enhancement despite the improvement of the CH₃NH₃PbI₃ film morphology. SEM study reveals that NH₄Ac and NaAc additives can both effectively improve perovskite film morphology by increasing the surface coverage via diminishing pinholes. The improvement on CH₃NH₃PbI₃ film morphology is beneficial for increasing the optical absorption of perovskite film and improving the interfacial contact at the perovskite/spiro-OMeTAD interface, leading to the increase of short-circuit current and consequently efficiency enhancement of the PSC device for NH₄Ac additive only.