Solution-processed all-small-molecule organic photovoltaics and photodetectors based on isoindigo derivatives

In this study, donor molecules featuring an isoindigo-based electron-deficient central core (TRA-IID-TRA) was used to compare its performance with that of a thienoisoindigo-based counterpart (TRA-TIID-TRA) when incorporated in solution process all-small-molecule-based organic optoelectronic devices. The energy level of the highest occupied molecular orbital of TRA-IID-TRA is deeper than that of TRA-TIID-TRA and has efficient light harvesting and greater carrier mobility and, thereby, organic photovoltaic performance over eight times greater than that of the TRA-TIID-TRA-derived device. The optimized organic photodetector (OPD) incorporating TRA-IID-TRA:PC71BM provided a detectivity (D*) of 1.8 x 1013 cm Hz1/2 W-1, a linear dynamic range of 106 dB, and rise/fall times of 2.7/1.3 mu s. These OPD properties are excellent in comparison with those previously reported for solution-processable all-small-molecule OPDs, suggesting that isoindigo has great potential for use as a building block for the fabrication of OPDs.