Polymorphic Phase Control Mechanism of Organic–Inorganic Hybrid Perovskite Engineered by Dual-Site Alloying

• Published in: Journal of physical chemistry. C Vol. 121; no. 17; pp. 9508 - 9515
• Main Authors: Jeon, Jiwon, Eom, Taedaehyeong, Lee, Eunyeong, Kim, Sol, Kim, Sanghak, Hong, Ki-Ha, Kim, Hyungjun
• Format: Journal Article
• Language: English
• Published: American Chemical Society 04.05.2017
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/acs.jpcc.7b03176

As a next-generation solar cell, perovskite solar cells (PSCs) have been attracting considerable attention. FAPbI3 is particularly considered as an optimal material with a proper band gap and thus has been employed as a base material for the PSCs with more than 20% efficiency; however, the competitive polymorphic growth of α- and δ-phases is a major hurdle in utilizing this material. To provide the theoretical model of the polymorphic phase competition of FAPbI3 for the first time, we here investigate how compositional engineering can pave a route to control the polymorphic growth of FAPbI3 using density functional theory combined with a statistical-mechanical treatment of the configurational space. We find that dual-site alloying of both cations and halides is critically important to achieve the specific stabilization of the α-phase while maintaining the good miscibility, thermodynamic stability, and optimal band gap property. Based on our first successful theoretical modeling of the FAPbI3 system and its polymorphic phase competition behavior during dual-site alloying, we anticipate deriving new rational guidelines on compositional engineering of organic–inorganic hybrid perovskite alloys for designing PSCs with high efficiencies and stabilities.