Structure–property relationship and design of carbazole naphthalene-based linear materials for organic and perovskite photovoltaics

To enhance the stability and efficiency of organic and perovskite solar cells, hole transport materials (HTMs) have garnered significant research attention. In this study, eight novel donor-based HTMs with a D-C-D-B-A (donor-core-donor-bridge-acceptor) architecture are designed by substituting the electronegative oxygen atom in the synthetic reference molecule AQ-R with various electron-withdrawing groups. This structural modification aimed to expand and fine-tune the photovoltaic and optoelectronic properties of organic and perovskite solar cells. Comprehensive computational analyses are conducted using density functional theory (DFT) and time-dependent (TD-DFT) approaches. The objective of all these analyses is to investigate the molecular geometries, optical properties, and photovoltaic performance. Key parameters that are determined include the molar absorption coefficient, frontier molecular orbitals, density of states, transition density matrix, electron density difference, light harvesting efficiency, excitation and binding energies, reorganization energies, and charge transfer characteristics. Furthermore, device-relevant properties such as open-circuit voltage, fill factor, and power conversion efficiency are estimated for the synthetic reference AQ-R and all designed materials (AQ-1-AQ-8). The newly developed HTMs (AQ-1 to AQ-8) showed lower excitation and binding energies, indicating their strong potential for efficient charge transport. Overall, this work highlights end-capped structural tuning as a promising strategy for optimizing donor materials, offering a viable pathway to boost the performance of organic and perovskite photovoltaics.