An asymmetrical thieno[2, 3-f]benzofuran (TBF)-based conjugated polymer for organic solar cells with high fill factor. (7th April 2017)

• Record Type: Journal Article
• Authors: He, Dingjun; Qiu, Lixia; Yuan, Jun; Zhang, Zhi-Guo; Li, Yongfang; Zou, Yingping
• Is Part Of: Polymer. Volume 114(2017)
• Page Start: 348
• Page End: 354
• Publication Date: 2017-04-07
• Subjects: Thieno[2, 3-f]benzofuran -- Alkylthio phenyl substitution -- Electron transporting layer -- Organic solar cells; Polymers -- Periodicals; Polymerization -- Periodicals; Polymères -- Périodiques; Polymérisation -- Périodiques; 547.7
• DOI: 10.1016/j.polymer.2017.03.001
• Languages: English
• ISSNs: 0032-3861

Abstract

Abstract: An asymmetrical building block-TBF modified with alkylthio phenyl as the side chain, polymerization with 4, 7-di (5-bromothiophen-2-yl)-5, 6-dioctyloxybenzo[c] [1, 2, 5]thiadiazole (BT), a new polymer-TBFPS-BT was obtained. As described in the UV-Vis spectrum, TBFPS-BT exhibited good absorption covering from 300 to 750 nm. Benefited from the alkylthio phenyl substitution, the polymer possessed deep HOMO level of −5.39 eV. The photoluminescence (PL) spectra indicated the generated excitons could be almost completely dissociation at the polymer/PC71 BM interface. Furthermore, the high and balanced mobility (1.49 × 10 −4 cm 2 V −1 s −1 for hole and 1.07 × 10 −4 cm 2 V −1 s −1 for electron) greatly contributed to enhance the fill factor (FF) and short-circuit current density ( J sc ) of device. PSC with different electron transporting layers (ETLs) were investigated, the results showed that when using perylene diimide (PDI) derivative with amino terminal substituent (PDIN) as ETL companied with 2% 1, 8-Diiodooctane (DIO), the device delivered a best PCE of 6.55% ( V oc = 0.8 V, J sc = 11.93 mA cm −2 and FF = 0.69). It is worth noting that all of the devices with ETLs and 2% DIO have shown high FFs over 0.65. So, the suitable modification on TBF and selection of ETLs were valid methods to improve device efficiency. Graphical abstract: With a new alkylthio phenyl substituted TBF polymer and PC[71]BM as the active layer, the best PCE for device of 6.55% was obtained with PDIN as ETL. Highlights: A new asymmetrical polymer based on alkylthio phenyl substituted TBF (TBFPS-BT) was designed and synthesized. TBFPS-BT/PC71 BM equipped with high and balanced mobilities for hole and electron under the optimized conditions. The device with PDIN as electron transporting layer, the PCE was increased to 6.55% with a high FF up to 0.69.