Enhanced photomultiplication of organic photodetectors: Via phosphorescent material incorporation

Photomultiplication organic photodetectors (PM-OPDs) were successfully constructed with a planar structure of PBDB-T/ITIC-Br as the active layer sandwiched by electrodes. Some isolated electron traps near the top surface of PBDB-T will be formed because small content ITIC-Br will permeate into PBDB-T layer prepared by sequential spin-coating method. The PM-OPDs achieve an external quantum efficiency (EQE) of 260% at 360 nm under a -9 V bias. The phosphorescent material FIrpic was incorporated into the PBDB-T layer to adjust the PBDB-T molecular arrangement for enhancing the hole mobility in the active layer. The optimal PM-OPDs with PBDB-T : FIrpic (100 : 10, wt/wt) display an EQE value of 2500% at 360 nm under a -9 V bias. A linear dynamic range (LDR) of 137 dB and a specific detectivity (D∗) of 4.2 × 1012 Jones are also achieved in PM-OPDs with PBDB-T : FIrpic (100 : 10, wt/wt). Moreover, high-quality imaging with the PM-OPDs as photosensitive element was realized by utilizing imaging systems without current preamplifiers, indicating that the PM-OPDs have potential applications in imaging.