Evolution of treated CdS/CdZnTe interface structures for CdZnTe based solar cells

The electrical energy generated by cadmium telluride (CdTe) solar panels is the most inexpensive energy within the photovoltaic technology industries and undermines fossil fuel-based energy resources across the world. This is owing to latest efficiency improvements carried out by alloying selenium (Se) into the absorber CdTe layer, and consequently, device efficiency reaches up to its current record of 23.1 %. Even though the Se-accumulation is understood to decrease the optical bandgap of the absorbing material layer, and increment in the short-circuit current, but only this accumulation does not enhance the device performance. Therefore, zinc (Zn) can be alloyed into the CdTe to make new trinary semiconductor cadmium zinc telluride (CdZnTe) material. This material can be used as absorber layer material in the single junction based solar cell device structures. So, we probe the evolution of the CdS/CdZnTe interface following post-annealing at 400 °C in different atmospheres, and correlate depth-resolved chemical changes with optical signatures and device performance. This combined spectroscopic–chemical–device study reveals interfacial mechanisms unique to CdZnTe and identifies annealing conditions that reduce recombination and improve device voltages and efficiencies. The maximum efficiency (9.78 %) was recorded for device treated in Ar + O 2 atmosphere and stability test of this device revealed that it has an efficiency of more than 91 % as compared to the initial efficiency original one's after 270 h. These outcomes may provide a route cast for further enhancement in the performance, which resulting even lower budgets for solar-generated electrical energy. • CdZnTe was employed as the absorber in single-junction CdS/CdZnTe solar cells. • Post-annealing improved grain growth, shifted the absorption edge, and red-shifted Raman peaks. • XPS depth profiling revealed S/Zn redistribution with oxygen incorporation at the interface. • EQE spectra confirmed enhanced wavelength-resolved carrier collection consistent with J-V data. • Ar + O 2 annealing yielded the highest efficiency among all post-treatments.