Effect of AISe quantum dots synthesis method and TiO2 substrate thickness on the performance of quantum dots-sensitized solar cells

This study reports the first synthesis of ternary AgInSe₂ (AISe) quantum dots using chemical precipitation at 90 °C and a combined precipitation–hydrothermal method in aqueous solution with glutathione capping. Three Ag:In ratios (1:6, 2:5, 3:4) were tested in the chemical precipitation method, showing that higher silver content caused a redshift in absorption and decreased bandgap energy. The TiO₂/AISe(1:6)/ZnS photoanode achieved a PCE of 0.56 %, which increased to 1.72 % using the hydrothermal approach. Optimizing TiO₂ thickness and the number of CdS deposition cycles enhanced light absorption, charge separation, and photocurrent density (12 mA/cm²) with an open-circuit voltage of 450 mV, yielding 4.2 % efficiency. Incorporating TiO₂ hollow spheres as a scattering layer further improved performance, achieving a maximum PCE of 5.55 %, representing a 46 % increase over cells without scattering layers. These results demonstrate the effectiveness of the optimized AISe-based QDSSC structure for high-performance solar energy conversion.