Material and Application of Semitransparent Organic Solar Cells

Semitransparent organic solar cells (ST-OSCs) harness abundant solar energy while transmitting visible light via the modification of layer structures and materials considering their characteristics and cost-effectiveness. Besides electrodes and charge transport layers, the key to determining the cell performance is the active layer structuralized as separate donor and acceptor layers or in bulk heterojunction (BHJ). Although bilayer cells can be optimized by modifying the layer thickness, interpenetration is preferred due to a shorter exciton diffusion length. In BHJ, non-fullerene acceptors gain the most benefits over fullerene derivatives and metal-related compounds due to the controllable absorption spectra and higher operation lifetime. Donors are made of conjugated polymers because of their electric conductivity and tunable properties. Till now, the power conversion efficiency (PCE) has reached 15% and the average visible transmittance (AVT) has exceeded 30%, showing an improvement in cell operation that encourages constructional, agricultural and bioelectronic applications. Properties and fabrication of present products such as building-integrated photovoltaics (BIPVs) and greenhouse rooftops, and health monitors, are analyzed. Future products such as emergency tents and heartbeat detectors have been explored to vitalize the market. Further commercialization requires attempts to overcome the tradeoff between PCE and AVT and enhance cell stability.