Side-chain engineering in naphthalenediimide-based n-type polymers for high-performance all-polymer photodetectors

A series of n-type semiconducting conjugated polymers based on naphthalene diimide (NDI) having three different side chains, 5-decylpentadecyl, 2-octyldodecyl and 4-(2-octyldodecyloxy) phenyl, were synthesized. Experimental results showed that the subtle structural changes at the side chains can influence the molecular packing, electron mobility, blend film morphology and thus performance of bulk-heterojunction polymer photodetectors using these NDI-based polymers as acceptors. The optimized all-polymer photodetector exhibited a specific detectivity (D*) of over 10(13) Jones in the spectral region of 300-800 nm under -0.1 V bias, which is among the best D* values of the reported UV-vis-NIR all-polymer photodetectors and comparable to the best fullerene-based photodetectors.