Nanoscale spatial mapping of charge carrier dynamics in perovskite solar cells. (August 2020)

• Record Type: Journal Article
• Authors: Bahrami, Behzad; Chowdhury, Ashraful Haider; Gurung, Ashim; Mabrouk, Sally; Reza, Khan Mamun; Rahman, Sheikh Ifatur; Pathak, Rajesh; Qiao, Qiquan
• Is Part Of: Nano today. Volume 33(2020)
• Publication Date: 2020-08
• Subjects: Perovskites -- Charge carrier dynamics -- Grain boundary -- Nanoscale mapping and ion migration; Nanotechnology -- Periodicals; Nanosciences -- Périodiques; 620.505
• DOI: 10.1016/j.nantod.2020.100874
• Languages: English
• ISSNs: 1748-0132

Abstract

Graphical abstract: Highlights: First time mapping of apparent carrier recombination lifetime, transport time and diffusion length simultaneously. Mapping with spatially resolved parameter leads the way for better understanding the role of grain boundaries at perovskite. Mix cation perovskite shows improved charge carrier dynamics at grain boundaries compared to MAPbI3 . Reduced density of traps in mix cation perovskite at grain boundaries implies less ion migration compared to MAPbI3 . Abstract: Charge carrier dynamics and behaviors are key parameters and need to be mapped at the nanoscale in order to search for correct materials for high-performance solar cells. Unfortunately, currently, there are no existing tools or capabilities that can simultaneously map charge carrier dynamics at nanometer range in solar cells. Here we use a Transient Photo-response AFM (TP-AFM) to map for the first time apparent carrier recombination lifetime (τr ), transport time (τt ) and diffusion length (LD ) in hybrid perovskites solar cells. These spatially resolved parameters reveal substantial variations at grain boundaries (GBs) of perovskites. Improved τr, τt and LD at GBs broaden the performance of these state-of-the-art mixed cation perovskites. Detail analysis of these parameters allow us to conclude that reduced density of trap states and recombination in mixed cation perovskites at GBs and its surrounding locations (extending to several nanometers into the grain interior) implies less ion migration. This first of its kind experimental realization of nanoscale mapping of charge carrier dynamics in photovoltaic materials can be used for applications in other optoelectronic devices.