Corrole-BODIPY Dyad as Small Molecule Donor for Bulk Heterojunction Solar Cell.

Dyes based on charge-transfer (CT) characteristics are attractive candidates for organic photovoltaics due to their intense and broad absorption window. In these molecular frame works, electron-rich donor and electron-deficient acceptor are covalently linked to achieve an effective CT process. Corrole, a tetrapyrrolic congener of porphyrin, is an excellent example of an electron rich molecule with a large molar extinction coefficient. BODIPY, on the other hand, is a well-known electron-deficient bypyrrolic boron difluoride complex with intense absorption complimentary to the corrole. A combination of these two structural motifs should results in a dyad having wide absorption window, which will be suitable for OPVs. Herein, a corrole derivative has been envisaged as an efficient donor for solution processed bulk heterojunction solar cell with PC71BM as an acceptor for the first time. The current molecule exhibits broad absorption in the visible range in solution as well as in thin films, with high molar extinction coefficient and a low band gap of 1.79 eV. Frontier molecular orbital energy levels were found to be complimentary with those of the well-known acceptor PC71BM. The optimized devices based on Cor-BODIPY : PC71BM showcased high power conversion efficiency (PCE) of 6.6 % with Jsc = 11.46 mA/ cm2 , Voc= 0.90 V and FF= 0.61. A remarkable value of incident photon to current conversion efficiency (IPCE) of 61% has also been observed.