Optimizing molecular alignment to reduce dark current via side-chain engineering for high-performance polymer photodetector

Abstract

Two low-bandgap polymers, PDTPN-α and PDTPN-β, containing diketopyrrolopyrrole (DPP) and dithienopyrrole (DTP) functionalized with two different side chains of α-naphthalene and β-naphthalene were synthesized. Experimental results show that subtle configuration changes at the side chains can effectively influence the molecular alignment, film morphology, and photodetector performance. As a result, the preferential edge-on orientation of PDTPN-β can effectively decrease the dark current density of the photodetector. This wealth of information on the strong correction between the variation in the molecular conformation and the device performance provides a novel avenue to prepare high-performance polymer photodetectors with superior specific detectivity.