Efficiency enhancement for solution-processed PbS quantum dots solar cells by inserting graphene oxide as hole-transporting and interface modifying layer

Interface modifying between the active layer and anode solar cells is a key technique to improve the device performance. In this paper, the enhancement of power conversion efficiency (PCE) of ZnO/PbS heterojunction quantum dot (QD) solar cells Au/PbS-TBAI/ZnO/ITO was achieved by incorporating a graphene oxide (GO) layer between the PbS-TBAI active film and the Au anode. Our experimental data showed the GO interlayer was partially reduced to graphene after its post-annealing at 140 °C and it played the role of hole-transporting layer and the interface-modifying layer. In this way, the defects existed at the contact interface of PbS-TBAI/Au were reduced significantly after inserting and post-annealing GO interlayer, resulting to the enhancement of holes transport and collection efficiency, showing a PCE enhancement of 12.87% as compared to that of the control device Au/PbS-TBAI/ZnO/ITO. The influence of post-annealing treatment on the whole device, as the reduction method for GO, on the performance of the QD solar cells was also explored and discussed.