Presentation Information
[8p-P01-2]Transition Metal-Induced Defect Engineering in Wide Bandgap Halide Double Perovskites Towards Enhanced Photophysical Properties.
〇(DC)Aakash Singh1, Sai santosh Kumar Raavi1, Santosh Gupta2 (1.Indian Institute of technology Hyderabad, 2.Bhabha Atomic research centre)
Keywords:
Halide double perovskite,DFT,Electron phonon coupling
Transition metal doping in halide double perovskite (CAIC) has emerged as an attractive approach to tailor their optoelectronic properties by defect engineering. In this work, we comprehensively explore the impact of Cu and Mn doping in CAIC through both experimental techniques and first-principles calculations. Cu doping, shown by DFT to preferentially substitute at the Ag site, Cu doping introduces shallow impurity states near the valence band maximum (VBM), leading to enhanced visible-light absorption. Positron annihilation lifetime spectroscopy (PALS) indicates the formation of anion vacancies. Additionally, variable-temperature PL measurements fit well to an Arrhenius model and a strong electron–phonon coupling, suggesting efficient thermal activation pathways. Mn doping also prefers Ag substitution, as confirmed by PALS and DFT, resulting in negative thermal quenching behavior due to efficient energy transfer from self-trapped excitons (STEs) to Mn ions. This behavior is accurately described using a two-term Arrhenius model. These findings collectively highlight the role of transition metal doping and defect engineering in modulating the electronic structure and emission properties of halide double perovskites, opening avenues for multifunctional applications in optoelectronics.