期刊
SCIENCE ADVANCES
卷 2, 期 10, 页码 -出版社
AMER ASSOC ADVANCEMENT SCIENCE
DOI: 10.1126/sciadv.1601650
关键词
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资金
- U.S. Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences [DE-SC0016144]
- Office of Science of the U.S. DOE [DE-AC02-05CH11231]
- NSF
- NIH/National Institute of General Medical Sciences via NSF [DMR-1332208]
- U.S. Department of Energy (DOE) [DE-SC0016144] Funding Source: U.S. Department of Energy (DOE)
A challenge of hybrid perovskite solar cells is device instability, which calls for an understanding of the perovskite structural stability and phase transitions. Using neutron diffraction and first-principles calculations on formamidinium lead iodide (FAPbI(3)), we show that the entropy contribution to the Gibbs free energy caused by isotropic rotations of the FA(+) cation plays a crucial role in the cubic-to-hexagonal structural phase transition. Furthermore, we observe that the cubic-to-hexagonal phase transition exhibits a large thermal hysteresis. Our first-principles calculations confirm the existence of a potential barrier between the cubic and hexagonal structures, which provides an explanation for the observed thermal hysteresis. By exploiting the potential barrier, we demonstrate kinetic trapping of the cubic phase, desirable for solar cells, even at 8.2 K by thermal quenching.
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