Grain Boundary Defect Passivation in Quadruple Cation Wide‐Bandgap Perovskite Solar Cells. Issue 4 (24th February 2021)

• Record Type: Journal Article
• Authors: Reza, Khan Mamun; Gurung, Ashim; Bahrami, Behzad; Chowdhury, Ashraful Haider; Ghimire, Nabin; Pathak, Rajesh; Rahman, Sheikh Ifatur; Laskar, Md Ashiqur Rahman; Chen, Ke; Bobba, Raja Sekhar; Lamsal, Buddhi Sagar; Biswas, Liton Kumar; Zhou, Yue; Logue, Brian; Qiao, Quinn
• Is Part Of: Solar RRL. Volume 5:Issue 4(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-02-24
• Subjects: defect passivation -- quadruple cations -- secondary growth -- wide-bandgap perovskites; Solar energy -- Periodicals; Photovoltaic power generation -- Periodicals; Solar energy -- Research -- Periodicals; Photovoltaic power generation -- Research -- Periodicals; Periodicals; 333.7923
• DOI: 10.1002/solr.202000740
• Languages: English
• ISSNs: 2367-198X

Abstract

Abstract : Development of high‐performance wide‐bandgap perovskites is a key component to enable tandem solar cells with either a silicon or low‐bandgap perovskites. However, the presence of defects in the Br‐rich wide‐bandgap perovskites, especially in the grain boundaries (GBs) has been particularly challenging and limits its performance. Herein, to accomplish the passivation of these defects, a combination of cation management with rubidium (Rb) introduction into the triple cation combination of cesium/formamidinium/methylammonium (CsFAMA) is exercised. Passivation is further enhanced by secondary growth (SG) using guanidinium iodide. In‐depth assessments of GB defect passivation are performed using Kelvin probe force microscopy (KPFM) and nanoscale charge‐carrier dynamics mappings provide insightful details on the presence of GBs defects and their suppression by the cation management and SG techniques. Reduction of unreacted PbX2 to realize a highly crystalline perovskite surface is achieved after incorporating Rb and SG treatment. As a result, a champion cell for 1.78 eV (FA0.79 MA0.16 Cs0.05 )0.95 Rb0.05 Pb(I0.6 Br0.4 )3 wide‐bandgap perovskite with an efficiency of 17.71% along with enhancement in all photovoltaic parameters is achieved. This study introduces a new way to analyze GB defects and reveals the consequence of defect passivation on charge‐carrier dynamics for realizing efficient perovskites. Abstract : This work presents effective grain boundary defect passivation in a 1.78 eV quadruple cation wide‐bandgap perovskite using a combination of two approaches for passivation: four cations (RbCsFAMA) and secondary growth (by guanidinium iodide) to achieve high efficiency.