The impact of the number of anchoring groups and the pattern of substitution on the efficacy of pyrene dyes in dye-sensitised solar cells - a theoretical investigation of multiple chemisorptions on TiO2 clusters

[Display omitted] •The first investigation of multiple chemisorptions of dyes on TiO2 clusters.•A strong influence of the number of anchoring groups on the photophysical properties.•The effects of substitution pattern on performance of pyrene-based dyes in DSSCs.•Increase of light harvesting efficiency by introducing more anchoring groups. This is the first exhaustive study of multiple chemisorptions on TiO2 clusters and the effects of the number of anchoring groups and substitution patterns on the efficacy of pyrene-based dyes in dye-sensitised solar cells (DSSCs). The study concentrates specifically on the chemisorption of several pyrene-based dyes on (TiO2)9 clusters functioning as electron acceptors in DSSCs. This research examines the geometries, electronic structures, absorption spectra, electron transfer, injection properties, and the overall efficacy of these dyes in dye-(TiO2)9 systems. Utilising density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations, the electronic and optical properties of pyrene dyes with various substitution patterns were analysed. The research centres on derivatives substituted at non-K positions of pyrene and nodal positions, including mono- and disubstituted isomers, as well as 1,3,7-trisubstituted and 1,3,6,8-tetrasubstituted derivatives. The results demonstrate that the number and position of the anchoring groups and the substitution pattern have a significant impact on the absorption and electron transfer properties of the dyes and, consequently, the overall performance of the DSSCs. These findings shed light on the design and optimisation of pyrene-based dyes for efficient DSSCs and the requirement for multiple chemisorptions on TiO2 clusters.