Foldable Semitransparent Organic Solar Cells for Photovoltaic and Photosynthesis

Semitransparent organic solar cells (ST-OSCs) have attracted extensive attention for their potential greenhouse applications. Conventional ST-OSCs are typically based on indium tin oxide (ITO) electrodes which suffer from mechanical brittleness. Therefore, alternatives for ITO are required for realization of foldable-flexible ST-OSCs (FST-OSCs). Herein, flexible poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) electrodes are prepared as ITO alternatives via polyhydroxy compound (xylitol) microdoping and acid treatment. As a result, flexible opaque OSCs based on PBDB-T-2F:Y6 photoactive system yield a high efficiency of 14.20%. The desirable optical properties of modified PEDOT:PSS electrodes in the visible light region and PBDB-T-2F:Y6 photoactive layer in the near-infrared region facilitate the fabrication of FST-OSCs with over 10% efficiency and 21% average visible light transmittance. Those FST-OSCs also display excellent mechanical stability against bending and folding due to the xylitol doping, where over 80% of the initial efficiency can still be maintained even after 1000 folding cycles. Meanwhile, parallel comparisons between plants grown under direct sunlight with a FST-OSCs roof and those under direct sunlight yield very similar results in terms of branch sturdiness and hypertrophic leaves. The results pave the way for realizing high-performing FST-OSCs based on PEDOT:PSS electrodes that could utilize visible light for plant growth and infrared light for power generation.