Alloyed quantum dots have garnered significant attention due to their tunable optoelectronic properties. In this research quaternary ZnCuInSe alloyed quantum dots (QDs) were synthesized through a novel controlled chemical precipitation method in an aqueous solution due to the low costs and ease of fabrication. The Cu/In molar ratio was mainly altered in a wide range to achieve ZnCuInSe QDs which are fully-optimized for application as light absorbing components in quantum dots sensitized solar cells (QDSSCs). Several characterizations were carried out and shown that the Cu/In molar ratio of 0.16 created the highest power conversion efficiency (PCE) of 4.47 %. This efficiency was just gained with utilization of ZnCuInSe QDs as light sensitizers in the photoanode structure. In continue, the synthesis and reflux time were changed in possible area for the preoptimized stoichiometric ratio of light absorbing QDs. It was demonstrated that ZnCuInSe nanoparticles synthesized at 3 h of reflux time in 95 ◦C could reveal the photovoltaic parameters of Jsc = 20.93 mA. Cm 2, Voc = 0.546 V, FF = 0.59 and PCE = 5.36 %. These improvements were finally justified due to the higher light harvesting efficiency and higher electron-hole lifetime which were measured within the pioneer cell.
