Accepting to Donate: NDI-Based Small Molecule as a Donor for Bulk Heterojunction Binary Solar Cells

A small molecular D-pi-A-pi-D triad NDIP consisting of naphthalenediimide (NDI) as an acceptor and porphyrin as a donor was synthesized. NDIP exhibits an intense absorption from visible to NIR region (400 nm to 1000 nm) with high molecular extinction coefficient. Endowed with excellent absorption and good charge carrier mobility, the molecule was used as a donor, against the normal perception as an acceptor due to the electron-deficient nature of NDI, in the binary bulk heterojunction solar cells with PCBM as an acceptor. The cell demonstrated remarkable power conversion efficiency of 8.45 % with extremely low E-loss of 0.40 eV, which is also the best recorded for NDI based small molecule organic solar cells.