Highly Sensitive Broad Light Response Organic Photodetectors from Pyrrolo[3,4‑c]pyrrole-1,4-dione-Based Conjugated Polymer with Noncovalent Conformational Locks

An alternating narrow bandgap conjugated polymer named POT-DPP, comprising pyrrolo­[3,4-c]­pyrrole-1,4-dione (DPP) derivatives and 3,3′-dimethoxy-2,2′-bithiophene, was developed and successfully employ in organic photodiode detectors (OPDs). The polymer POT-DPP exhibited ampliative light absorption (from 300 to 1070 nm) in the solid state with an increased dielectric constant of 6.31 at 1 kHz, an upshifted highest occupied molecular orbital (HOMO) energy level (−4.98 eV), and increased planarity of conjugated molecules as compared to that of the polymer PDQT without methoxy side chains. The OPDs based on PDT-DPP:PC71BM blends, present high specific detectivity (D*) over 1013 Jones from 300 to 900 nm, a high linear dynamic range (LDR) of 153 dB, and response speed of about 86.6–90.4 μs. Moreover, the optimization of the OPDs was systematically implemented by replacing the ZnO cathode layer with a ZnO/PFN bilayer and modifying the photoactive layer thickness. The OPDs achieved the highest D* of 1.23 × 1014 Jones at 562 nm with a large high D*­(over 1013) wavelength range from 300 to 900 nm with a 300 nm thick photoactive layer.