Balancing efficiency and transparency in organic transparent photovoltaics

The challenges in transparent photovoltaic (TPV) fields are still that the device transparency and efficiency are difficult to be balanced to meet the requirements of practical applications. In this study, we systematically investigated the interrelationship between photovoltaic film properties, optical transmission, and photovoltaic performances in the near-infrared harvesting organic TPVs. The results indicate that the photovoltaic film thickness determines the TPV's transparency and meanwhile affects the device efficiency; by contrast, the donor-acceptor ratio only affects device efficiency and has little effect on transparency. By controlling the film thickness and donor-acceptor ratio, the average visible transmission (AVT) of TPVs can be precisely managed in the range of 40% - 85%, and the device efficiency can achieve as high as 4.06% and 2.38% while the AVT exceeds 70% and 80%, respectively. Importantly, the large area (~10 cm²) TPV modules and ultra-flexible devices were then successfully prepared based on the systematical study.