Improved performance of inverted polymer solar cells using Cd2SSe/ZnS quantum dots

Quantum dots (QDs) materials have been widely used in polymer solar cells (PSCs) to improve device performance. In this paper, the enhanced efficiency of PSCs by incorporating Cd2SSe/ZnS (CSS-Z) QDs into active layer composed of Poly [N-9″-hepta-decanyl-2,7-carbazolealt- 5,5-(4′,7′-di-2-thienyl-2′,1′,3′-ben-zothiadiazole)] (PCDTBT): [6,6]-phenyl-C70-butyric acid methyl ester (PC71BM) were demonstrated, and the power conversion efficiency (PCE) of devices was increased from 5.72% to 6.75%, accounting for an 18% enhancement compared to the control device. The light trapping of optimized devices is higher than that of the control device, which is beneficial to boost the transport of photo-induced charges. Furthermore, the CSS-Z QDs play a role of charge transfer state, substantially improving exciton dissociation, charge transport, leading to an increased short-circuit current density (Jsc) and decreased series resistance (Rs).