Peripheral modifications of DTP-C6TH to attain dopant-free hole transporting materials of efficient photovoltaic properties

Abstract

Perovskite solar cells (PSCs) possess high potential to generate electricity. As, hole transport material (HTM) is the main factor of concern so, in current study, with the purpose of improving power efficiency ratio of PSCs, a series of five novel molecules, namely DTP1, DTP2, DTP3, DTP4 and DTP5 have been created computationally by structural modifications of dithieno [3,2-b:2′,3′-d]pyrol cored (DTP-C6TH) HTM. Five different electron-deficient acceptor moieties are substituted at the peripheral sites of the reference molecule (DTP-C6TH). To predict the efficiency of these newly fabricated molecules, their optoelectronic characteristics have been investigated by using MPW1PW91 DFT approach coupled to the basis set 6-31G (d, p). All structures are optimized by executing same DFT method by frontier molecular orbitals (FMOs) evaluations has been performed which suggests an excellent charge transport rate in all fabricated molecules (DTP1-DTP5). Further, density of states was studied that describes the involvement of all segments of recently designed molecules in the synthesis of molecular orbitals HOMO and LUMO. Results illustrate the energy gap estimations pertaining formulated molecules are significantly reduced relative to reference molecule (2.99 eV) with sequence of DTP5 = 2.29 eV > DTP1 = 2.11 eV > DTP2 = 2.04 > DTP3 = 1.93 eV > DTP4 = 1.73 eV. Absorption spectrum has been analyzed and a red shift in the wavelength is perceived  in all designed molecules (532–739 nm). Transition density matrix evaluations TDM, reorganizational energies (RE), open circuit voltage V_oc and power conversion efficiency (PCE) for all architecture molecules have been computed and it is concluded from the outcomes that these newly planned molecules possess efficient opto-electronic properties with enhanced PCE of up to 24.3% and can be used in future as HTMs for application in Perovskite solar cells.