New NIR Absorbing DPP-based Polymer for Thick Organic Solar Cells

New NIR Absorbing DPP-based Polymer for Thick Organic Solar Cells

Gulce Oklema , Xin Song, Levent Topparea, Derya Baran, Gorkem Gunbasa."New NIR Absorbing DPP-based Polymer for Thick Organic Solar Cells"​. Royal Society of Chemistry DOI: 10.1039/C8TC00113H​
Gulce Oklema, Xin Song, Levent Topparea, Derya Baran, Gorkem Gunbasa
Infrared, organic solar cells, selenophene
2018
​Sunlight covers a broad spectrum from ultra-violet to infra-red and low band gap materials are required to utilize the near infrared region (NIR) for better photon harvesting in organic solar cells. It has been shown that copolymers compromising diketopyrrolopyrrole based acceptors and simple donors (thiophene or furan) achieve absorption maximum around 800 nm. In this study, the selenophene based donor units coupled with diketopyrrolopyrrole acceptor unit based polymer (PFDPPSe) was synthesized with an absorption maximum at 830 nm and absorption onset of 930 nm. The optimized organic solar cells with PFDDPSe: PC71BM active layer blends of 210 nm showed maximum PCE of 6.16 % (ave. 6.02 %) via solvent additive engineering with inverted device structure. Charge transport, recombination loss mechanism, and morphology are systematically studied. These results demonstrate that highly efficient NIR polymer can be achieved by the introduction of selenophene and a suitable solvent additive process suitable for NIR organic solar cells. PFDPPSe is also one of the rare examples of a polymer with a PCE over 6% that does not contain any thiophene-based unit in its backbone.