Solar Conversion Efficiency Performance of a High Temperature Alloy over a Low Temperature One: Comprehending Interfaces through Excitonics Study

To take account of the interface in the nanocrystal (NC) materials, we have synthesized high quantum yield gradient CdZnSSe alloy NC having minimal involvement of interface (G-300) through high temperature (300 °C) pyrolysis and investigated the charge carrier dynamics. The performance was unraveled through femtosecond transient absorption studies. A gradient alloy of CdZnSSe (G-250) at low alloying temperature (250 °C) was also synthesized where several interfaces were present in the form CdSe/CdS/ZnSe/ZnS within the alloy material along with other deep traps as well as surface defects. The successful formulation of minimal involvement of interface in G-300 alloy has been envisaged through its blue-shifted optical absorption spectrum as compared to the G-250 alloy due to interionic diffusion of less reactive Zn and S toward the core of the material at elevated reaction temperatures that widen the band gap. Unlike the G-250 analogue, no charge transfer (CT) state was observed in the G-300 alloy, which als...