Implementation of bridged copolymerisation to optimise the optical properties of porphyrin: applications in dye-sensitized solar cells

This study explores the concept of all-organic sensitisation of dye-sensitized solar cells (DSSCs) by using a cosensitization approach to model efficient porphyrin-based photosensitizers. The aim is to enhance the absorption defects and light response current of porphyrin dyes, which have been reported in the literature. In this work, eight (8) natural porphyrin derivatives obtained through bridged copolymerisation of free base porphyrin and tetraazaporphyrin have been modelized and analysed. Their geometric parameters, stability energies, chemical stabilities, and photochemical properties were studied using density functional theory (DFT) methods in both gaseous and dichloromethane (DCM) phases. The analysis of photochemical properties, including maximum absorption wavelength (λmax), light harvesting efficiency (LHE), electron injection driving force (ΔGinj), regeneration driving force (ΔGreg), and excited state lifetime (τ) of the studied photosensitizers, show significant improvement compared to the parent dye (free base porphyrin) and some recent derivatives SM315 and YD2-o-C8. It is worth noting that the eight (8) modelled dyes from porphyrin show broader LHE curves not only compared to the parent dye, but also compared to the SM315 dye, which may lead to a higher running photo density. This study highlights the effectiveness of bridged copolymerisation for developing high-performance DSSCS based on porphyrin.