Regulating carrier transfer and performance in dye-sensitized solar cells (DSSCS) using gamma-irradiated chitosan@pva@al2o3 nanocomposites as a counter electrode

This study investigates the use of gamma-irradiated Chitosan@PVA@Al₂O₃ (CPA) composites as counter electrodes (CEs) to enhance charge transfer and efficiency in dye-sensitized solar cells (DSSCs). CPA films were exposed to in-situ gamma irradiation at dosages ranging from 0 to 30 KGy to optimize their physicochemical and microstructural features. The effect of gamma irradiation on the structural and morphological features of the composite, as well as its influence on the charge transfer resistance and photovoltaic performance of DSSCs, was extensively studied. The SEM micrographs reveal changes in surface morphology and porosity as the irradiation dose increases. The surface features of the irradiated CE hybrids also gradually enhanced as the gamma dosage increased, reaching the desired levels at 25 KGy (average roughness (Ra) = 7.87 µm, apparent porosity = 79.4 %, and bulk density = 1.68 g/cm³). The interaction of high-energy gamma photons created promising conditions for charge separation, minimizing recombination and enhancing charge carrier mobility within the CPA composites. These improvements in mobility and the reduction of resistive losses contributed to an extended cell lifespan and more efficient charge transfer. Interestingly, surface modification at 25 KGy resulted in an optimized efficiency of 8.25 % and a short-circuit photocurrent density (J_sc) of 18.056 mA/cm², reflecting a 37.76 % increase compared to the untreated sample. This enhancement in photovoltaic performance is attributed to the generation of oxygen-enriched free radicals within the CPA structure, which facilitated the formation of continuous pathways for efficient electron transport. This work highlights the pivotal role of gamma-irradiated CPA catalytic CEs in advancing DSSC performance and presents a novel strategy for enhancing the efficiency of these devices.