Crystallinity and Defect Reduction in Cs₂AgBiBr₆ : Key Factors for Enhanced Optoelectronic Devices

Cs₂AgBiBr₆ double perovskites have emerged as promising materials for optoelectronic applications due to their unique structural and electronic properties. This study systematically compares two crystal growth techniques-Single Crystal Growth (SCG) and Seed-assisted Growth (SAG) to evaluate their impact on crystal quality, defect density, and optoelectronic performance. While both methods yield similarly sized crystals, the SAG method produces superior-quality crystals with reduced defects, improved crystallinity, and enhanced structural coherence. Comprehensive characterization using X-ray diffraction (XRD), photoluminescence (PL), time-resolved photoluminescence (TRPL), impedance spectroscopy, and current-voltage (I-V) measurements reveals that SAG-grown crystals exhibit lower lattice strain, fewer trap states, and higher charge carrier mobility. These improvements translate into a 2.5-fold increase in photocurrent response and a significantly lower dark current in photodetectors based on SAG-grown crystals. The results highlight the SAG method as a more effective and reproducible approach for fabricating high-quality Cs2AgBiBr6 single crystals, making them ideal for advanced optoelectronic devices such as photodetectors and light-emitting components.