Tailoring Crystal Structure of FA0.83Cs0.17PbI3 Perovskite Through Guanidinium Doping for Enhanced Performance and Tunable Hysteresis of Planar Perovskite Solar Cells

• Published in: Advanced functional materials Vol. 29; no. 1
• Main Authors: Pham, Ngoc Duy, Zhang, Chunmei, Tiong, Vincent Tiing, Zhang, Shengli, Will, Geoffrey, Bou, Agustín, Bisquert, Juan, Shaw, Paul E., Du, Aijun, Wilson, Gregory J, Wang, Hongxia
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 04.01.2019
• Subjects: band energy alignment; Cations; Cesium; Crystal structure; Dopants; efficiency enhancement; Electric potential; Energy conversion efficiency; guanidinium ion doping; Hysteresis; Ion charge; Ion recombination; Materials science; Performance enhancement; Performance measurement; perovskite solar cells; Perovskites; Photovoltaic cells; Solar cells; tunable hysteresis
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.201806479

Current–voltage hysteresis of perovskite solar cells (PSCs) has raised the concern of accurate performance measurement in practice. Although various theories have been proposed to elucidate this phenomenon, the origin of hysteresis is still an open question. Herein, the use of guanidinium cation (Gu+)‐dopant is demonstrated to tailor the crystal structure of mixed‐cation formamidinium‐cesium lead triiodide (FA0.83Cs0.17PbI3) perovskite, resulting in an improved energy conversion efficiency and tunable current–voltage hysteresis characteristic in planar solar cells. Particularly, when the concentration of Gu‐dopant for the perovskite film increases, the normal hysteresis initially observed in the pristine PSC is first suppressed with 2%‐Gu‐dopant, then changed to inverted hysteresis with a higher Gu‐dopant. The hysteresis tunability behavior is attributed to the interplay of charge/ion accumulation and recombination at interfaces in the PSC. Furthermore, compared to the cell without Gu+‐dopant, the optimal content of 2% Gu+‐dopant also increases the device efficiency by 14%, reaching over 17% under one sun illumination. A new method to control current–voltage hysteresis of planar structured FA0.83Cs0.17PbI3 perovskite solar cells (PSCs) is presented while enhancing device efficiency through tailoring the crystal structure of the perovskite compound with a guanidinium cation (Gu+)‐dopant. New insights into the correlation of the dynamics of device hysteresis with the interfacial charge recombination and accumulation in the PSCs are revealed.