Donor-acceptor polymer for the design of All-Solid-State dye-sensitized solar cells

Density functional theory study has been carried out to design a new All-Solid-State dye-sensitized solar cell (SDSC), by applying a donor-acceptor conjugated polymer instead of liquid electrolyte. The typical redox mediator (I1-/I3-) is replaced with a narrow band gap, hole transporting material (HTM). The electronic and optical properties predict that donor and acceptor moieties in the polymeric body have increased the visible light absorption and charge transporting ability, compared to their parent polymers. A unique "upstairs" like band energy diagram is created by packing N3 between HTM and TiO2. Upon light irradiation on the proposed configuration, electrons will move from the dye to TiO2 and from HTM to dye (to regenerate dye), simultaneously. Our theoretical simulations prove that the proposed configuration will be highly efficient as the HOMO level of HTM is 1.19 eV above the HOMO of sanitizer (dye); providing an efficient pathway for charge transfer. High short-circuit current density and power conversion efficiency is promised from the strong overlapping of molecular orbitals of HTM and sensitizer. A low reorganization energy of 0.21 eV and exciton binding energy of 0.55 eV, confirm the high efficiency of HTM. Finally, a theoretical open-circuit voltage of 1.49 eV would results high quantum yield while, the chemical stability of HTM towards oxidation can be estimated from its high ionization potential value (4.57 eV). (C) 2016 Elsevier B.V. All rights reserved.