title: Evaluating the Optoelectronic Quality of Hybrid Perovskites by Conductive Atomic Force Microscopy with Noise Spectroscopy.
abstract: Organic-inorganic hybrid perovskite solar cells have emerged as promising candidates for next-generation solar cells. To attain high photovoltaic efficiency, reducing the defects in perovskites is crucial along with a uniform coating of the films. Also, evaluating the quality of synthesized perovskites via facile and adequate methods is important as well. Herein, CH3NH3PbI3perovskites were synthesized by applying second solvent dripping to nonstoichiometric precursors containing excess CH3NH3I. The resulting perovskite films exhibited a larger average grain size with a better crystallinity compared to that from stoichiometric precursors. As a result, the performance of planar perovskite solar cells was significantly improved, achieving an efficiency of 14.3%. Furthermore, perovskite films were effectively analyzed using a conductive AFM and noise spectroscopy, which have been uncommon in the field of perovskite solar cells. Comparing the topography and photocurrent maps, the variation of photocurrents in nanoscale was systematically investigated, and a linear relationship between the grain size and photocurrent was revealed. Also, noise analyses with a conductive probe enabled examination of the defect density of perovskites at specific grain interiors by excluding the grain-boundary effect, and reduced defects were clearly observed for the perovskites using CH3NH3I-rich precursors.
authors: Byungho
authors: B
authors: Lee
authors: Sangheon
authors: S
authors: Lee
authors: Duckhyung
authors: D
authors: Cho
authors: Jinhyun
authors: J
authors: Kim
authors: Taehyun
authors: T
authors: Hwang
authors: Kyung Hwan
authors: KH
authors: Kim
authors: Seunghun
authors: S
authors: Hong
authors: Department of Materials Science and Engineering, Dankook University , Cheonan, Chungnam 31116, Korea.
authors: Taeho
authors: T
authors: Moon
authors: Byungwoo
authors: B
authors: Park
keywords: conductive AFM; excess CH3NH3I; grain size; noise spectroscopy; perovskite solar cells