Molecular engineering of Y123-based photosensitizers and copper redox couples for dye-sensitized solar cells: Theoretical perspectives

Abstract

In this work, five new copper redox couples are constructed with modifying the [Cu(dmp)₂]^2+/1+ complex, and their oxidation potentials and diffusion coefficients are evaluated in detail by means of DFT calculations and molecular dynamics simulation. Furthermore, five novel D-A-π-A type organic dyes based on Y123 have been designed and their total power conversion efficiencies are theoretically evaluated. The estimated parameters included the short-circuit current density (J_SC), open-circuit voltage (V_OC), filling factor (FF), and power conversion efficiency (η). Results show that introducing auxiliary electron acceptor can significantly reduce the LUMO energy level of Y123, narrow its HOMO-LUMO gap, and greatly expand its light absorption range. All estimated values for Y123 dye nicely match the available experimental ones with small deviations. More importantly, our calculations reveal that the η values of designed dye YN and YS are as high as 20.1% and 15.0%, which is much higher than that (10.0%) of Y123 dye, indicating that these two dyes are potential candidates as efficient photosensitizers. The current work not only finds several promising organic dyes, but also provides a new scheme for developing organic dyes with improved properties in efficient DSSC devices.