Unprecedented low energy losses in organic solar cells with high external quantum efficiencies by employing non-fullerene electron acceptors. Issue 28 (5th July 2017)

• Record Type: Journal Article
• Authors: Mishra, Amaresh; Keshtov, Mukhamed L.; Looser, Annika; Singhal, Rahul; Stolte, Matthias; Würthner, Frank; Bäuerle, Peter; Sharma, Ganesh D.
• Is Part Of: Journal of materials chemistry. Volume 5:Issue 28(2017)
• Page Start: 14887
• Page End: 14897
• Publication Date: 2017-07-05
• Subjects: Materials -- Research -- Periodicals; Chemistry, Analytic -- Periodicals; Environmental sciences -- Research -- Periodicals; 543.0284
• DOI: 10.1039/c7ta04703g
• Languages: English
• ISSNs: 2050-7488

Abstract

Abstract : Non-fullerene molecular acceptors in combination with a polymeric donor gave well performing BHJSCs with energy losses below 0.4 eV concomitant with outstanding external quantum efficiencies in the NIR-regime. Abstract : In order to realize high photocurrent generation in the low-energy region of the solar spectrum, two conjugated A–D–A oligomers, PY-1 andDCI-2 comprising a central dithieno[3, 2- b :2′, 3′- d ]pyrrole donor (D) unit and end-capping acceptors (A) 1-butyl-4-methyl-2, 6-dioxopyridine-3-carbonitrile (PY) or 3-dicyanomethyleneindan-1-one (DCI) have been synthesized and characterized. The oligomers showed strong absorptions in the red and near-IR region in solution and in the solid state. As a consequence of the strong electron-accepting character, the absorption band ofDCI-2 in thin films is significantly red-shifted compared to that ofPY-1 resulting in a low optical energy gap of 1.23 eV. In optimized solution-processed bulk-heterojunction solar cells using a polymeric donorP1, the new non-fullerene acceptorDCI-2 provides an excellent power conversion efficiency of 6.94% which is noticeably higher than that ofPY-1 -based devices (PCE = 4.89%). Most importantly, a high open-circuit voltage ( V OC ) of ∼0.8 V with unprecedented energy losses, between the optical energy gap and the open-circuit voltage, between 0.39 and 0.43 eV concomitant with excellent external quantum efficiencies of 69%@880 nm in the NIR-regime have been achieved forDCI-2 -based devices.