Highly efficient hole transporting pyrimidine-based dyes for photovoltaic applications: A DFT/TD-DFT study

In this study, we evaluated the photovoltaic performance of pyrimidine-based dyes for dye-sensitized solar cells (DSSCs) using density functional theory (DFT) and time-dependent (TD)-DFT calculations. Structural analysis revealed that these dyes exhibit planar geometries and bind to the TiO2 surface via coordinate and secondary bonds. Charge density difference analysis indicated favorable interactions between TiO2 and the dyes, facilitating electron injection into TiO2. All dyes showed negative binding energies, indicating thermodynamically favorable binding. Frontier molecular orbital analysis was conducted to identify energy level distributions essential for determining performance parameters. The hole transport performance of the studied dyes was assessed based on their hole reorganization energies, all of which exhibited lower values, indicating faster hole transport. The absorption spectra of dye-TiO2 systems predicted a bathochromic shift after dye adsorption, conducive to improved photovoltaic performance. Among the dyes studied, ATT-Pyri emerged as the best performer in DSSCs, displaying favorable reactivity descriptors, a longer excited-state lifetime, minimum total reorganization energy, and broader absorption spectra. Notably, ATT-Pyri demonstrated enhanced photovoltaic performance parameters, making it a promising candidate for DSSC applications, potentially optimizing device efficiency.