Broadband polymer photodetectors with a good trade-off between broad response and high detectivity by using combined electron-deficient moieties†
High-performance broadband photodetectors based on low-bandgap conjugated polymers are scarce due to a trade-off between the photoresponse range and device performance. In this work, the polymers with structural features responsible for both broad response and high detectivity are realized by using the combined electron deficient moieties at the molecular level. Based on the electron-deficient diketopyrrolopyrrole (DPP) and benzothiadiazole (BT), the combined units of DPP–DPP and DPP–BT–DPP are deemed more electron deficient and were successfully incorporated into the corresponding polymers. The arrangement of electron deficient moieties in the polymer main chain was found to be able to greatly affect the absorption profile, energy level, molecular stacking, and blend film morphology. Consequently, the photodetector based on the polymer with a DPP–BT–DPP acceptor exhibited a D* value of over 1012 Jones in the spectral region of 320–930 nm under −0.1 V bias.