Temperature Dependence of the Piezophototronic Effect in CdS Nanowires

The piezophototronic effect is known as a three-way coupling between piezoelectric polarization, semiconductor property, and optical excitation in piezoelectric semiconductor materials to modify their energy band structures by strain-induced piezoelectric polarization charges, and thus to tune/control their optoelectronic processes of charge carrier generation, separation, recombination, and transport. In this work, the temperature dependence of the piezophototronic effect in wurtzite-structured CdS nanowires is investigated from 77 to 300 K. The piezophototronic effect is enhanced by over 550% under lower temperature due to the increased effective piezoelectric polarization surface/interface charges resulting from the reduced screening effect by decreased mobile charge carriers in CdS nanowires. Optoelectronic performances of CdS nanowires are systematically investigated under various light illuminations, strains, and temperatures. By analyzing the corresponding band diagrams, the piezophototronic effect is found to dominate the transport and separation processes of charge carriers. This study presents in-depth fundamental understanding about the piezophototronic effect and provides guidance for its future applications in optoelectronic devices.