Latest Progress on Photoabsorbent Materials for Multifunctional Semitransparent Organic Solar Cells

Semi-transparent organic solar cells (ST-OSCs) have revolutionized the field of photovoltaics (PVs) due to their unique abilities, such as transparency and color tunability, and have transformed normal power-harvesting OSC devices into multifunctional devices, such as building-integrated photovoltaics, agrivoltaics, floating photovoltaics, and wearable electronics. Very recently, ST-OSCs have seen remarkable progress, with a rapid increase in power conversion efficiency from below 7% to 12-14%, with an average visible transparency of 9-25%, especially due to the use of low bandgap semiconductors including polymer donors and non-fullerene acceptors that exhibit absorption in the near-infrared region as photoabsorbent materials. From this perspective, the latest developments in ST-OSCs stemming from the innovations in photovoltaic materials that delivered multifunctional ST-OSCs with top-of-the-line power conversion efficiencies are discussed to shed light on the structure-property relationship between molecular design and current challenges in this cutting-edge research field. Finally, personal perspectives, including research directions for the future use of ST-OSCs in multifunctional applications, are also proposed.