Lead-Free Cs2AgBiCl6 Double Perovskite: Experimental and Theoretical Insights into the Self-Trapping for Optoelectronic Applications

Swati N Rahane; Ganesh K Rahane; Animesh Mandal; Yogesh Jadhav; Akshat Godha; Avinash Rokade; Shruti Shah; Yogesh Hase; Ashish Waghmare; Nilesh G Saykar; Anurag Roy; Kranti N Salgaonkar; Deepak Dubal; Surendra K Makineni; Nelson Y Dzade; Sandesh R Jadkar; Sachin R Rondiya

doi:10.1021/acsphyschemau.4c00008

Lead-Free Cs₂AgBiCl₆ Double Perovskite: Experimental and Theoretical Insights into the Self-Trapping for Optoelectronic Applications

ACS Phys Chem Au. 2024 Jul 5;4(5):476-489. doi: 10.1021/acsphyschemau.4c00008. eCollection 2024 Sep 25.

Authors

Swati N Rahane¹, Ganesh K Rahane², Animesh Mandal², Yogesh Jadhav³, Akshat Godha², Avinash Rokade¹, Shruti Shah¹, Yogesh Hase¹, Ashish Waghmare¹, Nilesh G Saykar², Anurag Roy⁴, Kranti N Salgaonkar^{5

6}, Deepak Dubal^{7

8}, Surendra K Makineni², Nelson Y Dzade⁹, Sandesh R Jadkar¹, Sachin R Rondiya²

Affiliations

¹ Department of Physics, Savitribai Phule Pune University, Pune 411007, India.
² Department of Materials Engineering, Indian Institute of Science, Bangalore 560012, India.
³ Symbiosis Center for Nanoscience and Nanotechnology (SCNN), Symbiosis International (Deemed University) (SIU), Lavale, Pune 412115 Maharashtra, India.
⁴ Solar Energy Research Group, Environment and Sustainability Institute, University of Exeter, Penryn Campus, Cornwall TR10 9FE, U.K.
⁵ Catalysis and Inorganic Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411008, India.
⁶ Academic of Scientific and Innovative Research (AcSIR), Pune 411008, India.
⁷ School of Chemistry and Physics, Queensland University of Technology (QUT), Brisbane, Queensland 4000, Australia.
⁸ Centre for Materials Science, Queensland University of Technology (QUT), 2 George Street, Brisbane, Queensland 4000, Australia.
⁹ Department of Energy and Mineral Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, United States.

Abstract

Lead-free double perovskites (DPs) will emerge as viable and environmentally safe substitutes for Pb-halide perovskites, demonstrating stability and nontoxicity if their optoelectronic property is greatly improved. Doping has been experimentally validated as a powerful tool for enhancing optoelectronic properties and concurrently reducing the defect state density in DP materials. Fundamental understanding of the optical properties of DPs, particularly the self-trapped exciton (STEs) dynamics, plays a critical role in a range of optoelectronic applications. Our study investigates how Fe doping influences the structural and optical properties of Cs₂AgBiCl₆ DPs by understanding their STEs dynamics, which is currently lacking in the literature. A combined experimental-computational approach is employed to investigate the optoelectronic properties of pure and doped Cs₂AgBiCl₆ (Fe-Cs₂AgBiCl₆) perovskites. Successful incorporation of Fe³⁺ ions is confirmed by X-ray diffraction and Raman spectroscopy. Moreover, the Fe-Cs₂AgBiCl₆ DPs exhibit strong absorption from below 400 nm up to 700 nm, indicating sub-band gap state transitions originating from surface defects. Photoluminescence (PL) analysis demonstrates a significant enhancement in the PL intensity, attributed to an increased radiative recombination rate and higher STE density. The radiative kinetics and average lifetime are investigated by the time-resolved PL (TRPL) method; in addition, temperature-dependent PL measurements provide valuable insights into activation energy and exciton-phonon coupling strength. Our findings will not only deepen our understanding of charge carrier dynamics associated with STEs but also pave the way for the design of some promising perovskite materials for use in optoelectronics and photocatalysis.