Exploration of promising optical and electronic properties of (non-polymer) small donor molecules for organic solar cells

Muhammad Khalid, Muhammad Usman Khan, Saeed Ahmed, Zahid Shafiq, Mohammed Mujahid Alam, Muhammad Imran, Ataualpa Albert Carmo Braga, Muhammad Safwan Akram

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Abstract

Non-fullerene based organic compounds are considered promising materials for the fabrication of modern photovoltaic materials. Non-fullerene-based organic solar cells comprise of good photochemical and thermal stability along with longer device lifetimes as compared to fullerene-based compounds. Five new non-fullerene donor molecules were designed keeping in view the excellent donor properties of 3-bis(4-(2-ethylhexyl)-thiophen-2-yl)-5,7-bis(2ethylhexyl) benzo[1,2-:4,5-c′]-dithiophene-4,8-dione thiophene-alkoxy benzene-thiophene indenedione (BDD-IN) by end-capped modifications. Photovoltaic and electronic characteristics of studied molecules were determined by employing density functional theory (DFT) and time dependent density functional theory (TD-DFT). Subsequently, obtained results were compared with the reference molecule BDD-IN. The designed molecules presented lower energy difference (ΔΕ) in the range of 2.17–2.39 eV in comparison to BDD-IN (= 2.72 eV). Moreover, insight from the frontier molecular orbital (FMO) analysis disclosed that central acceptors are responsible for the charge transformation. The designed molecules were found with higher λmax values and lower transition energies than BDD-IN molecule due to stronger end-capped acceptors. Open circuit voltage (Voc) was observed in the higher range (1.54–1.78 V) in accordance with HOMOdonor–LUMOPC61BM by designed compounds when compared with BDD-IN (1.28 V). Similarly, lower reorganization energy values were exhibited by the designed compounds in the range of λe(0.00285–0.00370 Eh) and λh(0.00847–0.00802 Eh) than BDD-IN [λe(0.00700 Eh) and λh(0.00889 Eh)]. These measurements show that the designed compounds are promising candidates for incorporation into solar cell devices, which would benefit from better hole and electron mobility.

Original languageEnglish
Article number21540
JournalScientific Reports
Volume11
Issue number1
DOIs
Publication statusPublished - 2 Nov 2021

Bibliographical note

Funding Information:
M. M. A and M. I. express appreciation to the Deanship of Scientific Research at King Khalid University Saudi Arabia through a research groups program under Grant Number R.G.P. 1/356/42. A.A.C.B. (Grants 2015/01491-3 and 2014/25770-6) is thankful to Fundacão de Amparo à Pesquisa do Estado de Sao Paulo for financial support. A.A.C.B. (Grant 312550/2020-0) also thanks the Brazilian National Research Council (CNPq) for financial support and fellowships. This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nivel Superior do Brasil (CAPES) Finance Code 001.

Publisher Copyright:
© 2021, The Author(s).

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