A deconvoluted PL approach to probe the charge carrier dynamics of the grain interior and grain boundary of a perovskite film for perovskite solar cell applications. Issue 13 (20th March 2017)

• Record Type: Journal Article
• Authors: Mamun, Abdullah Al; Ava, Tanzila Tasnim; Jeong, Hyeon Jun; Jeong, Mun Seok; Namkoong, Gon
• Is Part Of: Physical chemistry chemical physics. Volume 19:Issue 13(2017)
• Page Start: 9143
• Page End: 9148
• Publication Date: 2017-03-20
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/c7cp01140g
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : 2D photoluminescence (PL) mapping revealed the blueshift of PL at grain boundaries while relatively very uniform but longer wavelengths were observed at grain interiors. Abstract : We explore a new characterization approach capable of probing the grain interior (GI) and grain boundary (GB) of a CH3 NH3 PbI3− x Cl x perovskite thin film. In particular, we have found that the photoluminescence (PL) spectrum observed for a CH3 NH3 PbI3− x Cl x perovskite thin film is asymmetric, and can be deconvoluted using a bi-Gaussian function, representing the ordered and disordered phases of the perovskite film. In order to understand the origin of the ordered and disordered phases of the perovskite film, two-dimensional (2D) PL mapping was performed to resolve the PL spectra at the nanoscale level. Quantitative analysis of the local PL spectra revealed that the ordered phase originated from the GIs while the disordered phase mainly came from the GBs. In particular, power-dependent PL measurements of the deconvoluted PL spectra revealed that smaller grained perovskites showed defect-mediated recombination at GBs but exciton-like transitions at GIs. In contrast, perovskite films with large grains followed an excellent power law, showing exciton-like recombination at both GIs and GBs. As expected, perovskite solar cells fabricated with large grains showed an increased efficiency with higher light absorption and higher charge extraction efficiency.