title: Nucleation and Crystal Growth of Organic-Inorganic Lead Halide Perovskites under Different Relative Humidity.
abstract: Organic-inorganic lead halide perovskite compounds are very promising materials for high-efficiency perovskite solar cells. But how to fabricate high-quality perovksite films under controlled humidity conditions is still an important issue due to their sensitivity to moisture. In this study, we investigated the influence of ambient humidity on crystallization and surface morphology of one-step spin-coated perovskite films, as well as the performance of solar cells based on these perovskite films. On the basis of experimental analyses and thin film growth theory, we conclude that the influence of ambient humidity on nucleation at spin-coating stage is quite different from that on crystal growth at annealing stage. At the spin-coating stage, high nucleation density induced by high supersaturation prefers to appear under anhydrous circumstances, resulting in layer growth and high coverage of perovskite films. But at the annealing stage, the modest supersaturation benefits formation of perovskite films with good crystallinity. The films spin-coated under low relative humidity (RH) followed by annealing under high RH show an increase of crystallinity and improved performance of devices. Therefore, a mechanism of fast nucleation followed by modest crystal growth (high supersaturation at spin-coating stage and modest supersaturation at annealing stage) is suggested in the formation of high-quality perovskite films.
authors: ‡School of Mechanical and Electronic Engineering, Jingdezhen Ceramic Institute, Jingdezhen 333001, P. R. China.
authors: Hao
authors: H
authors: Gao
authors: Chunxiong
authors: C
authors: Bao
authors: Faming
authors: F
authors: Li
authors: §Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, P. R. China.|∥Jiangsu Key Laboratory for Nanotechnology, Nanjing University, Nanjing 210093, P. R. China.
authors: Tao
authors: T
authors: Yu
authors: Jie
authors: J
authors: Yang
authors: Weidong
authors: W
authors: Zhu
authors: Xiaoxin
authors: X
authors: Zhou
authors: Gao
authors: G
authors: Fu
authors: §Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, P. R. China.|∥Jiangsu Key Laboratory for Nanotechnology, Nanjing University, Nanjing 210093, P. R. China.
authors: Zhigang
authors: Z
authors: Zou
keywords: ambient humidity; crystal growth; film coverage; methylammonium lead trihalide; nucleation density