Large Gain, Low Noise Nanocomposite Ultraviolet Photodetectors with a Linear Dynamic Range of 120 dB

reduced dark current enabled a constant responsivity from light intensity of 10 −2 Wcm −2 all the way down to 12 pWcm −2 , resulting in a very large linear dynamic range of 90 dB. [ 5 ] However, the insertion of 25 nm C-TPD between PEDOT:PSS and C 60 interface also blocked the tunneling of electrons (secondary electron injection) into C 60 even under large reverse bias of –6 V, and thus annulled the gain of C 60 photodetectors. In this manuscript, we report on a fullerene based photodetector with both large gain and low noise, enabled by the introduced C-TPD:ZnO nanocomposite buffer layer between the PEDOT:PSS and C 60 layer. As a result, a record large linear dynamic range of 120 dB was achieved in these organic photodetectors which almost doubles that of the state-of-the-art commercial inorganic UV solid-state photodetectors. The device structure used here is shown in Figure 1 (a), which is composed of ITO (cathode)/PEDOT:PSS (35 nm)/CTPD:ZnO (weight ratio 1:1) (30 nm)/C 60 (80 nm)/BCP (10 nm)/ Al (anode) (100 nm). The C-TPD was formed via a thermal annealing assisted hydrolysis process of TPD-Si 2 , and its chemical structure is shown in Figure 1 (b). C 60 was chosen as the photoactive material for its demonstrated high photoconductive gain and strong absorption in the ultraviolet–blue range. [ 4a ]