Co-doping is an effective strategy to optimise the photovoltaic performance of GQDs. However, due to the heterogeneity of GQDs, it is difficult to achieve controllable photovoltaic performance without determining the structure-property relationship. In this work, we perform first-principles calculations to investigate the optoelectronic properties of GQDs doped with S, B, and P atoms. Our results show that S doping is crucial for tuning the photoelectric performance of S,B and S,P co-doped GQDs. Increasing the polarity of the solvent improves the charge transfer performance of single P-doped GQDs. Moreover, single P-doped GQDs show better photovoltaic performance than other doping configurations. Furthermore, the addition of B co-dopants to GQDs with Sh doping configuration improves the energy conversion of GQDs compared to B doping alone. Our study provides guidance for the rational design of GQDs for various photovoltaic applications.