Synergistic photocurrent addition in hybrid quantum dot: Bulk heterojunction solar cells

Abstract

We investigate the effect of a thin PbS quantum dot (QD) layer on the performance of hybrid quantum-dot-organic solar cells (QD-OSCs). The PbS QD layer is able to function as a photosensitizing layer to improve short circuit current density (J(sc)) and power conversion efficiency (PCE) by exploiting solar flux in the near infrared region up to 1100 nm. The increase in J(sc) is well represented by changes observed in the external quantum efficiency of devices with and without the PbS QD layer, including the region of the first exciton transition where only the PbS QD layer absorbs. Remarkably, enhanced performance was observed in QD-OSCs consisting of just a 13 nm thick PbS QD layer and 150 nm PTB7:PC71BM layer, exhibiting a J(sc) of 17.0 mA cm(-2), and PCE of 8.30% (8.58% for champion device) compared to reference devices without PbS QD which produced a J(sc) of 15.4 mA cm(-2) and PCE of 7.56%. (C) 2015 Elsevier Ltd. All rights reserved