Incorporating Potassium Citrate to Improve the Performance of Tin‐Lead Perovskite Solar Cells

• Published in: Advanced energy materials Vol. 13; no. 32
• Main Authors: Chen, Lei, Li, Chongwen, Xian, Yeming, Fu, Sheng, Abudulimu, Abasi, Li, Deng‐Bing, Friedl, Jared D., Li, You, Neupane, Sabin, Tumusange, Marie Solange, Sun, Nannan, Wang, Xiaoming, Ellingson, Randy J., Heben, Michael J., Podraza, Nikolas J., Song, Zhaoning, Yan, Yanfa
• Format: Journal Article
• Language: English
• Published: 01.08.2023
• Subjects: all‐perovskite tandem solar cells; buried interface; defect passivation; low‐bandgap perovskites
• ISSN: 1614-6832; 1614-6840
• DOI: 10.1002/aenm.202301218

Easy‐to‐form tin vacancies at the buried interface of tin‐lead perovskites hinder the performance of low‐bandgap perovskite solar cells (PSCs). Here, a synergistic strategy by incorporating potassium citrate (PC) into the poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) hole‐transport layer to passivate the buried interface of Sn‐Pb PSCs is reported. PC neutralizes the acidity of PEDOT:PSS and stabilizes the perovskite front surface, enhancing device stability. Citrate moieties coordinate with Sn2+ on the buried perovskite surface, preventing Sn2+ oxidation and suppressing defect formation. Additionally, potassium cations incorporate into Sn‐Pb perovskites, enhancing crystallinity and passivating halide defects. The combined benefits enable efficient low‐bandgap Sn‐Pb PSCs with a power conversion efficiency of 22.7% and a high open‐circuit voltage of 0.894 V. Using this method, 26.1% efficiency for all‐perovskite tandem solar cells is demonstrated. These results emphasize the significance of buried interface passivation in developing efficient and stable Sn‐Pb PSCs and all‐perovskite tandem solar cells. Potassium citrate (PC) is incorporated into the poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) hole‐transport layer to passivate the buried interface of tin‐lead perovskites. PC neutralizes the acidity of PEDOT:PSS and coordinates with Sn/Pb cations, preventing oxidation of Sn2+ and enhancing interface properties. This strategy enables power conversion efficiencies of 22.7% and 26.1% for Sn‐Pb and all‐perovskite tandem solar cells, respectively.