We report an all-polymer photodiode comprising a new electron-transporting polymer, PNNTH, that contains naphthalene diimide and thiazole moieties. PNNTH has strong absorption at around 670 nm and an electron mobility of ≈10−4 cm2 V−1 s−1. Bulk heterojunction films composed of PNNTH blended with the donor polymer, PBDTT-FTTE, in a weight ratio of 1:2 were found to have electron and hole mobilities of ≈10−5 cm2 V−1 s−1 and ≈10−4 cm2 V−1 s−1, respectively. The photoresponse of conventional and inverted organic photodiodes containing the blend could be tuned from broadband (400–800 nm) to narrowband (50 nm full-width-at-half-maximum) simply by changing the thickness of the all-polymer blend. The narrowband response was achieved using the charge collection narrowing mechanism, which was enhanced by the unbalanced charge mobility. Transfer matrix-based optical modelling confirmed the wavelength dependence of the photoresponse. For both the broadband and narrowband photodiodes, the specific detectivity was greater than 1011 Jones.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- Mathematical Physics
- Condensed Matter Physics