Efficient Semitransparent Organic Solar Modules with Exceptional Diurnal Stability through Asymmetric Interaction Induced by Symmetric Molecular Structure

The symmetry‐breaking design strategy of nonfullerene acceptor can improve the performance of semitransparent organic solar cells (ST‐OSCs). However, no report exists on the ‘asymmetric molecular interaction’ induced by symmetric molecular structure in nonfullerene acceptors. Herein, we showcase that 2D fluorophenyl outer groups in symmetric 4FY promote dipole‐driven self‐assembly through asymmetric molecular interactions, resulting in a tighter packed structure than Y6 with the same symmetric geometry. Such unique properties lead to high‐performance layer‐by‐layer OSCs, accompanied by simultaneously reduced energy and recombination losses and improved charge‐related characteristics. ST‐OSCs based on PCE10‐2F/4FY achieve notable power conversion efficiency (PCE) of 10.81%, average visible transmittance of 45.43%, and light utilization efficiency (LUE) of 4.91%. Moreover, exceptional diurnal cycling stability is observed in the ST‐OSCs based on PCE10‐2F/4FY with much prolonged T80 up to 134 h, which is about 17 times greater than the reference PCE10‐2F/Y6. Lastly, we fabricate highly efficient semitransparent organic solar modules based on PCE10‐2F/4FY (active area of 18 cm2), which shows PCE of 6.78% and the highest LUE of 3.10% to date for all‐narrow bandgap semitransparent organic solar modules. This work demonstrates that asymmetry‐driven molecular interactions can be leveraged to fabricate large‐area ST‐OSCs that are efficient and stable under realistic operating conditions.