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

P R Nitha; V Jayadev; Sourava C Pradhan; Velayudhan V Divya; Cherumuttathu H Suresh; Jubi John; Suraj Soman; Ayyappanpillai Ajayaghosh

doi:10.1002/asia.202000808

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

Chem Asian J. 2020 Nov 2;15(21):3503-3512. doi: 10.1002/asia.202000808. Epub 2020 Oct 6.

Authors

P R Nitha^{1

2}, V Jayadev^{1

2}, Sourava C Pradhan^{1

2}, Velayudhan V Divya^{1

2}, Cherumuttathu H Suresh^{1

2}, Jubi John^{1

2}, Suraj Soman^{1

2}, Ayyappanpillai Ajayaghosh^{1

2}

Affiliations

¹ Chemical Sciences and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology (CSIR-NIIST), Thiruvananthapuram, 695019, India.
² Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India.

PMID: 32910559
DOI: 10.1002/asia.202000808

Abstract

Three metal-free organic D-π-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 dye-sensitized 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.

Keywords: Back electron transfer; Benzothieno(3,2-b)indole; Dye sensitized solar cell; Indolo(3,2-b)indole; π-spacer.

Abstract

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