Molecular engineering of Diketopyrrolopyrrole-based photosensitizer for solution processed small molecule bulk heterojunction solar cells

• Published in: Solar energy materials and solar cells 2011-07, Vol.95 (7), p.1731-1740
• Main Authors: Jeong, Ban-Seok, Choi, Hyunbong, Cho, Nara, Min Ko, Haye, Lim, Woocherl, Song, Kihyung, Kwan Lee, Jae, Ko, Jaejung
• Format: Article
• Language: English
• Subjects: Applied sciences; Bulk heterojunction solar cell; Derivatives; Direct energy conversion and energy accumulation; Electric potential; Electrical engineering. Electrical power engineering; Electrical power engineering; Elevated; Energy; Exact sciences and technology; Hole mobility; Molecular engineering; Natural energy; Photoelectric conversion; Photovoltaic cells; Photovoltaic conversion; Small molecule; Solar cells; Solar cells. Photoelectrochemical cells; Solar energy; Voltage
• ISSN: 0927-0248; 1879-3398
• DOI: 10.1016/j.solmat.2011.01.041

New symmetrical low band-gap small molecule materials, DPP-bis[ter-3HT-TPA] and DPP-bis[ter-3HT] as novel derivatives of Diketopyrrolopyrrole–thiophene with/without triphenylamine (TPA) end group have been synthesized and characterized. And the effects of TPA moiety were investigated. Compared to DPP-bis[ter-3HT], DPP-bis[ter-3HT-TPA] shows red-shifted absorption and significantly higher molar absorption coefficient. And the HOMO level of DPP-bis[ter-3HT-TPA] is elevated than DPP-bis[ter-3HT]. Moreover, DPP-bis[ter-3HT-TPA] exhibited one order higher hole mobility than DPP-bis[ter-3HT], suggesting that TPA contributes to a better hole mobility. The bulk-heterojunction photovoltaic devices with DPP-bis[ter-3HT-TPA] showed better efficiencies than DPP-bis[ter-3HT], showing the best power-conversion efficiency (PCE) of 1.5% (±0.12) under 100 mW/cm 2 with a short-circuit current ( J sc )=5.73 mA/cm 2, a fill factor ( FF)=0.45, and an open-circuit voltage ( V oc )=0.59 mV. New symmetrical low band-gap small molecule materials, DPP-bis[ter-3HT-TPA] and DPP-bis[ter-3HT] as novel derivatives of Diketopyrrolopyrrole-thiophene with/without triphenylamine (TPA) end group have been synthesized and characterized. And the effects of TPA moiety were investigated. Ban-Seok Jeong, Hyunbong Choi, Nara Cho, Haye Min Ko, Woo cherl Lim, Kihyung Song, Jae Kwan Lee, Jaejung Ko. [Display omitted] ►New low band-gap small molecule material, DPP-bis[ter-3HT-TPA] as novel derivatives of Diketopyrrolopyrrole–thiophene with triphenylamine end group exhibited significantly enhanced hole-mobility. ► The triphenylamine motif for small molecule BHJ materials contributes to a better hole mobility. ► The triphenylamine motif plays an important role as effective electron-donating and hole transporting mediator in organic photovoltaics.