Correlating Chemical Structure and Charge Carrier Dynamics in Phenanthrocarbazole-Based Hole Transporting Materials for Efficient Perovskite Solar Cells

Abstract

Polymeric hole transport materials (HTMs) have emerged because of their potential to produce dopant-free, efficient, and stable perovskite solar cells (PSCs). Therefore, we engineered 10 novel donor materials (SMH1–SMH10) containing phenanthrocarbazole-based polymeric structures for organic and PSCs. These molecules underwent bridging-core modifications using different spacers, such as furan (N1), pyrrole (N2), benzene (N3), pyrazine (N4), dioxane (N5), isoxazole (N6), isoindole (N7), indolizine (N8), double bond (N9), and pyrimidine (N10), in comparison to reference molecule R. The study examined the structure–property relationship and the impact of these modifications on the optical, photovoltaic, photophysical, and optoelectronic characteristics of the newly designed SMH1–SMH10 series. Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations were conducted to analyze frontier molecular orbitals, density of states, reorganization energies, open-circuit voltage, transition density matrix, and charge transfer processes. Results show that the newly designed molecules (SMH1–SMH10) exhibited superior optoelectronics characteristics compared to the R molecule. Among these, SMH4 is the most promising candidate, with a small band gap (2.79 eV), low electron and hole mobility (λ_e 0.0028 eV, λ_h 0.0020 eV), lower binding energy (E_b 0.58 eV), high λ_max values (656.42 nm in gas, 573.34 nm in chlorobenzene), and a high V_oc of 1.30 V. Therefore, this study demonstrated that bridging-core modifications offer a simple and effective strategy for designing desirable characteristics molecules for photovoltaic applications.