Multi-dimensional interfacial engineering for a practical large-area transparent flexible organic photovoltaics

Although the efficiency improvement by the research of interlayer and photo-active layer in the field of organic photovoltaics has been achieved, the practical research for commercialization to be applied in a large area, flexible and transparent module is still rare and lagging behind. Herein, we present a flexible and semitransparent large area photovoltaic with a high-performance by engineering the charge transport with a molecular linker as an organic interfacial layer. The insertion of a molecular linker between the electron transporting layer and the organic active layer led to a considerable increase in power conversion efficiency as well as an improvement in stability and flexibility. We also compared the device performance after 100 days, there is an 80% decrease in photovoltaic efficiency. However, after the inclusion of the molecular linker, there is only a 10% decrease. The molecular linker can bond well the electron transporting layer and photo-active layer to improve mechanical durability. We also tested with various photo-active layer conditions (thickness) and module types (area and number of cells). After charge transport engineering, we obtained improved results for all conditions. Finally, with this charge transport engineering, we obtained a remarkably high figure of merit for transparent flexible organic photovoltaic mini-modules which has 41.45% transmittance with an efficiency of 8.22% for sub-(50 mm x 70 mm) and 6.43% for sub-(100 mm x 100 mm) modules. This FOM is higher than the reported studies. For application we made a convergence module (100 mm x 100 mm) which composed electrochromic and photovoltaic. As a result, there is a self-powered EC-PV convergence module well-operated under the light. It could potentially be applied to smart window systems.