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 AISebased QDSSC structure for high-performance solar energy conversion.
