Broadband photomultiplication-type polymer photodetectors and its application in light-controlled circuit

Photomultiplication-type polymer photodetectors (PM-PPDs) were achieved with polymer P3HT as donor and PY3Se-1V as acceptor based on structure of ITO/PEDOT:PSS/active layer/Al. The optimal weight ratio of P3HT to PY3Se-1V is about 100:3. Amounts of isolated electron traps are formed with PY3Se-1V surrounded by P3HT due to rather less content of PY3Se-1V in active layers and about 0.94 eV energy offset between the lowest unoccupied molecular orbitals (LUMO) of P3HT and PY3Se-1V. The optimal PM-PPDs exhibit broad spectral response from 350 to 950 nm and external quantum efficiency (EQE) values of 68,200% at 360 nm, 26,400% at 630 nm and 19,500% at 850 nm under −15 V bias. The working mechanism of PM-PPDs is attributed to the interfacial trap-assisted hole tunneling injection from external circuit. The performance of PM-PPDs can be further improved by incorporating appropriate PMBBDT with high hole mobility as the third component. The EQE values of optimal ternary PM-PPDs are increased to 105,000% at 360 nm, 40,000% at 630 nm and 31,800% at 850 nm under −15 V bias, benefiting from the enhanced hole transport in ternary active layers. The optimal ternary PM-PPDs were successfully applied in a light-controlled circuit to turn on or turn off light emitting diode (LED).