Novel Two-Dimensional Conjugated Polymer Containing Fluorinated Bithiophene as Donor and Benzoselenodiazole as Acceptor Units with Vinyl-Terthiophene Pendants for Polymer Photovoltaic Cells

Abstract

Novel two-dimensional conjugated copolymer, abbreviated as PDTBSeVTT-2TF, containing electron-deficient 4,7-di(thiophen-2-yl)benzo[c][1,2,5]selenodiazole (DTBSe) unit, conjugated vinyl-terthiophene (VTT) side chain and 3,3′-difluoro-2,2′-bithiophene (2TF) was designed and synthesized using microwave-assisted Stille cross-coupling polymerization. UV–visible absorption and cyclic voltammetry studies revealed that this copolymer possesses a strong and broad absorption in the range of 300–800 nm and a narrow optical bandgap (Eg) of 1.57 eV with low-lying HOMO and LUMO energy levels. Further, the bulk heterojunction polymer solar cells (PSCs) were fabricated using PDTBSeVTT-2TF as donor and [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) as acceptor with an inverted device structure of ITO/ZnO/PDTBSeVTT-2TF:PC71BM/V2O5/Ag. The processing temperature of blend solution for preparing PDTBSeVTT-2TF:PC71BM active layer showed obvious impact on the photovoltaic performance of solar devices. The cell fabricated from the blend solution at 65 °C exhibited enhanced power conversion efficiencies (PCE) of 5.11% with a Jsc of 10.99 mA/cm−2 compared with the one at 50 °C, which had a PCE of 4.69% with a Jsc of 10.10 mA/cm−2. This enhancement is due to the dissolution of PDTBSeVTT-2TF clusters into single molecules and small aggregates, improving the miscibility between the polymer and PC71BM and thus increasing the donor/acceptor interface.

Electrochromic Devices Based on Poly(2,6-di(9H-carbazol-9-yl)pyridine)-Type Polymer Films and PEDOT-PSS

“…Organic electroactive materials (OEM) have played a role in science and commercial electronic devices due to their benefits of facile processing, flexibility of molecular design and synthesis, and reversibility between oxidation and reduction processes [1]. Conjugated polymers (CPs) were widely-studied organic electroactive materials due to their potential applications in supercapacitors [2], light-emitting diodes [3,4,5], electrochromic devices (ECDs) [6,7,8], solar cells [9,10], fluorescent sensors [11,12], catalysts for methanol electroxidation [13,14,15], and organic transistors [16]. Among these applications, scientists have focused immensely in ECDs by virtue of their multicolour and energy-saving characteristics after applying a voltage [17].…”

Zwitter-Ionic Polymer Applied as Electron Transportation Layer for Improving the Performance of Polymer Solar Cells

“…Polymer solar cells (PSCs) with a bulk heterojunction (BHJ) structure have attracted extensive research attention owing to advantages, such as light-weight, low cost, flexibility, and large-area fabrication [ 1 , 2 ]. Recently, the power conversion efficiencies (PCEs) of single-junction PSCs have reached 13% [ 3 , 4 , 5 , 6 ], owing to the molecular design of photoactive materials [ 3 , 7 , 8 , 9 , 10 , 11 , 12 ], interface engineering [ 13 , 14 , 15 , 16 ], and improvement of device configurations. Although the design of new photoactive materials plays a key role in this concern, the steps for exploration of high efficient interfacial materials that can facilitate the charge collection and transportation have never ceased.…”