Regulating Back Electron Transfer through Donor and π‐Spacer Alterations in Benzothieno[3,2‐b]indole‐based Dye‐sensitized Solar Cells

Abstract

Three metal-free organic DÀ πÀ A dyes with benzothieno[3,2-b]indole as electron donor, cyanoacrylic acid as both electron acceptor and anchoring group with benzene (BID-1), thiophene (BID-2) and furan (BID-3) as π-spacers were designed and synthesized for application in dyesensitized solar cells (DSSCs). A planar and electron-rich heterocycle such as benzothieno[3,2-b]indole offers better backbone rigidity and improves charge transport properties in comparison to indolo[3,2-b]indole donor, previously reported from our group. Additionally, we synthesized a benzothieno[3,2-b]indole donor grafted with longer alkyl chains which efficiently prevented the approach of oxidized species in the electrolyte coming closer to semiconductor thereby arresting recombination. A power conversion efficiency of 4.11 % was achieved for dye-sensitized solar cells based on the furan π-spacer benzothieno[3,2-b]indole dye BID-3 in comparison to the corresponding indolo[3,2-b]indole dye (IID-3) having an efficiency of 1.71 %. Detailed interfacial electrical measurements along with theoretical calculations disclosed the mechanism of back electron transfer and improvement in photovoltaic performance with respect to variation in both donor and π-spacer.

Novel multifunctional unimolecular initiators built on natural indole featuring fast photobleaching and visible light/thermal double polymerization

“…As an abundant green renewable resource extracted from the flower oils of jasmine, 25 bitter orange blossom and daffodil, indole is principally employed as an extended conjugated pyrrole derivative in biomedicine, 26,[27][28][29][30] chemical enzyme catalysis, 31 fine chemicals, 32 optoelectronics, 33 and dyestuffs. 34 Concurrently, the characteristics of an electronrich structure with low oxidation potential and a large conjugation system 35 enable it to be a promising candidate as an electron donor unit for the design of efficient PIs. 14,36 A series of charge transfer complexes 37 between indoles (donors) and iodonium salt (acceptor) presented excellent dual thermal and photochemical free radical polymerization initiation for benchmarked methacrylates.…”

Role of π-spacer in regulating the photovoltaic performance of copper electrolyte dye-sensitized solar cells using triphenylimidazole dyes

“…There have been continued efforts to further improve efficiency of DSSCs using diverse structural frames such as D-D-π-A and D-A-π-A systems. [19][20][21][22] With the same strategy, our group reported four D-π-A system (D1-D4) based metal-free organic sensitizers, where, phenanthroimidazole acts as a donor and either cyanoacrylic acid or rhodanine-3-acetic acid acts as acceptors that shows impressive PCEs up to 10.2% in the presence of co-adsorbent…”

Synthesis of Novel Artemisinin Derivatives and Their Electrochemical Properties

“…Carbazoles, thiophenes, indoles and pyridines are well known examples [37–40] . Moreover, heterocyclic compounds are core motifs for renewable energy sources due to their low molecular weight, flexibility, wide absorption bands, stable electrochemical stability, environmentally friendly, and reusability [41,42] …”

“…[37][38][39][40] Moreover, heterocyclic compounds are core motifs for renewable energy sources due to their low molecular weight, flexibility, wide absorption bands, stable electrochemical stability, environmentally friendly, and reusability. [41,42] Artemisinin a natural endoperoxide isolated from the plant Artemisia annua L, is widely used as an anti-malaria drug and their derivatives have anti-bacterial, anti-inflammatory, and anti-tumor activities. [27][28][29][30] Artemisinin exhibited greater activities than other antivirals, so it is known as the most effective drug in the treatment of malaria.…”