Au-doped single layer graphene nanoribbons for a record-high efficiency ITO-free tandem polymer solar cell

Abstract

Polymer solar cells (PSCs) are apparently becoming one of the leading technologies to reduce our dependency on traditional power sources. However, the frequent use of a transparent conductive electrode, indium-tin-oxide (ITO), in the present PSC technologies has increased the overall expenses. In addition, its brittleness in nature could limit the future development of PSCs, particularly in a flexible format. Here, we report on the development of Au-doped single layer graphene nanoribbons (Au-doped SLGNRs) as an option to the transparent conducting electrode (indium tin oxide, ITO) that could yield a single-layer PSC with power conversion and external quantum efficiencies comparable to commonly used transparent electrodes. When the Au-doped SLGNRs are implemented in tandem architecture, a power conversion efficiency (PCE) of 8.48% is achieved. This is the highest efficiency for ITO-free tandem PSCs to date. The improved performance of the Au-doped SLGNR anode is characterized to the structure of the device that enables a hole transport from the active layer into the Au-doped SLGNR anode.