Colloidal InP and ZnS-coated InP quantum dots (QDs) were synthesized by hot injection method and successfully employed as sensitizer for the first time in quantum dot sensitized solar cells (QDSSCs). Colloidal InP QDs has not been used in QDSSCs due to low stability and high sensitivity to the moisture. In this work ZnS-coating were applied as a strategy to increase the stability and protect InP against moisture and interaction with electrolyte. The nature of low toxicity of such QDs compared to high toxic Cd-based QDs was the main idea to employ “green” and heavy metal-free InP-ZnS QDs for future solar cell application. It is found that ZnS shell-coating caused the absorption onset to shift toward longer wavelength and broader absorption. In the solar cell device, ZnS shell not only acts as protection agent and increases the life time for InP QDs but also enhances the power conversion efficiency by more than 2 times.