Vol.:(0123456789) Optical and Quantum Electronics (2020) 52:364 https://doi.org/10.1007/s11082-020-02482-7 1 3 Molecular engineering of A–D–C–D–A configured small molecular acceptors (SMAs) with promising photovoltaic properties for high‑efficiency fullerene‑free organic solar cells Riaz Hussain 1  · Faiza Hassan 2  · Muhammad Usman Khan 1,3  · Muhammad Yasir Mehboob 1  · Rafia Fatima 2  · Muhammad Khalid 4  · Khalid Mahmood 5  · Chaudhary Jahrukh Tariq 4  · Muhammad Nadeem Akhtar 6 Received: 26 April 2020 / Accepted: 15 July 2020 / Published online: 23 July 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020 Abstract Non fullerene small acceptor molecules in organic photovoltaics are proven beneficial than the traditional fullerene based acceptors for their fine contribution in organic solar cells. Researchers are constantly doing efforts for designing novel acceptor materials with prom- ising photovoltaic properties. Designing of novel molecules by end-capped modifications is a convenient strategy to obtain high efficiency acceptor molecules for OSCs. Herein, we studied optoelectronic characteristics of five novel acceptor–donor–core–donor–acceptor configured small acceptor molecules (S1–S5) after end-capped modifications of recently synthesized DF-PCIC molecule. Designed molecules S1–S5 consist of 1,4-difluorobenzene (as central core), 4,4-bis(2-ethylhexyl)-2,6-dimethyl-4H-cyclopenta[1,2-b:5,4-b′]dithio- phene as donor which directly attached with different end-capped acceptors. The electronic and optical properties of newly designed (S1–S5) molecules are examined and compared with reference molecule with the aid of DFT and TD-DFT. Certain key parameters like frontier molecular orbitals analysis, density of states, dipole moment, binding energy along Electronic supplementary material The online version of this article (https://doi.org/10.1007/s1108 2-020-02482-7) contains supplementary material, which is available to authorized users. * Riaz Hussain riazhussain@uo.edu.pk * Muhammad Usman Khan usman.chemistry@gmail.com; usmankhan@uo.edu.pk 1 Department of Chemistry, University of Okara, Okara 56300, Pakistan 2 Department of Chemistry, The University of Lahore, Lahore, Pakistan 3 Department of Applied Chemistry, Government College University, Faisalabad 38000, Pakistan 4 Department of Chemistry, Khwaja Fareed University of Engineering and Information Technology, Rahim Yar Khan 64200, Pakistan 5 Institute of Chemical Sciences, Bahauddin Zakariya University, Multan 60800, Pakistan 6 Department of Chemistry, The Islamia University of Bahawalpur, Baghdad-ul-Jadeed Campus, Bahawalpur 63100, Pakistan