Solution processable high-performance infrared organic photodetector by iodine doping

Solution processable high-performance, large-area, low-cost infrared organic photodetectors (OPDs) have been receiving more and more attention for their important applications both in scientific and technological fields. The search for a simple method to upgrade device performance for OPDs becomes increasingly important. Here, the performance of an OPD in the near-infrared (NIR) region is tremendously improved by doping iodine into the device's active layer (P3HT:PCBM:I-2), 2.7 wt% iodine doping may increase the absorption by 31.3% for the active film and result in a similar to 11 000-fold increase in responsivity for the detector. A high detectivity (D*) of similar to 1.6 x 10(12) cm Hz(1/2) W-1, a good specific responsivity (R) of similar to 80 A W-1 and a large EQE (external quantum efficiency) of 120% are achieved under illumination (lambda = 850 nm) at room temperature. Systematic characterizations reveal that iodine-doping can introduce acceptor states in the energy band gap for the polymer layer, and thus increase the harvesting to long wavelength photons. A small dose of iodine doping can significantly induce improvement in device performance. This work demonstrates a simple but feasible method to enhance an NIR optoelectronics device.