100 cm2 Organic Photovoltaic Cells with 23% Efficiency under Indoor Illumination

The application of organic photovoltaic (OPV) cells to drive off-grid microelectronic devices under indoor light has attracted broad attention. As organic semiconductors intrinsically have less ordered intermolecular packing than inorganic materials, the relatively larger energetic disorder is one of the main results that limit the photovoltaic efficiency of the OPV cells at low carrier density. Here, we optimize the alkyl chains of non-fullerene acceptors to get suppressed energetic disorder. We find the optimal acceptor DTz-R1 with the shortest alkyl chain has the strongest crystalline property and lowest energetic disorder. As a result, over 26% efficiency is recorded for the 1 cm(2) OPV cells under a light-emitting diode illumination of 500 lux. We also fabricate a 100 cm(2) cell device and get a PCE of 23.0%, which is an outstanding value for large-area OPV cells. These results suggest that modulation of the energetic disorder is of great importance for further improving the efficiency of OPV cells, especially for indoor applications.