Grain Boundary Defect Passivation in Quadruple Cation Wide-Bandgap Perovskite Solar Cells

Khan Mamun Reza, Ashim Gurung, Behzad Bahrami, Ashraful Haider Chowdhury, Nabin Ghimire, Rajesh Pathak, Sheikh Ifatur Rahman, Md Ashiqur Rahman Laskar, Ke Chen, Raja Sekhar Bobba, Buddhi Sagar Lamsal, Liton Kumar Biswas, Yue Zhou, Brian Logue, Quinn Qiao

Research output: Contribution to journalArticlepeer-review

20 Scopus citations


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 (FA0.79MA0.16Cs0.05)0.95Rb0.05Pb(I0.6Br0.4)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.

Original languageEnglish (US)
Article number2000740
JournalSolar RRL
Issue number4
StatePublished - Apr 2021


  • defect passivation
  • quadruple cations
  • secondary growth
  • wide-bandgap perovskites

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering


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