Simulation of electronic and optical properties of polyene-diphenylaniline-sensitizers for perovskite n-ZnTiO3 towards efficient dye sensitized solar cells

Abstract

Four polyene-diphenylaniline dyes (D5, D7, D9 and D11) are simulated here, for the first time, as sensitizers for nano-ZnTiO3-based dye-sensitized solar cells (DSSCs). First-principles calculations method has been used to describe dye-semiconductor surface interactions. Bonding between the ZnTiO3 nanoparticle, considered as (ZnTiO3)8 cluster, is studied using density-functional theory (DFT) and time-dependent (TD-DFT). Dye parameters have been used in analyzing electron-transfer processes from dye excited molecules into semiconductor. Electronic structures and simulated UV–Vis spectra of four dyes (isolated and ZnTiO3-bound forms) are described together with energy level diagrams and electrochemical parameters. Results are compared with earlier experimental results and used to discuss parameters that affect DSSC performance. The excited D11 (with −2.0173 eV level) has highest electron injection rate toward the ZnTiO3 conduction band. D9 (with −0.5369 eV level) is regenerated, by I−/I3−redox couple, more efficiently than D5, D7 and D11 dyes, with minimal charge-recombination rates. Moreover, D9 displays highest peak absorption, in both free form (at 544 nm) and adsorbed form (at 563 nm). D5 and D9 exhibit high Light Harvesting Efficiency values 0.7752 and 0.8416, respectively, between dye LUMO and ZnTiO3 conduction-band, compared to D7 (0.4921) and D11 (0.5441). D9 exhibits highest open-circuit potential (VOC, 0.88 eV) while D5, D7 and D11 have 0.79, 0.47 and 0.29 eV, respectively. The D9@ZnTiO3 interface shows highest stability with largest adsorption energy (−47.16 eV, −4550.62 kJ/mol) among different systems. Results indicate that D9@ZnTiO3-based DSSCs should exhibit highest power conversion efficiency (PCE) among the series.