DFT and multivariate statistical analysis for the rational design of DTP-based hole transport materials

Conventional hole-transport materials (HTMs) in perovskite solar cells (PSCs) often suffer from limited charge transport, suboptimal energy alignment, and recombination losses. This paper presents a computational molecular-design and screening approach for DTP-based HTMs using density functional theory (DFT) and multivariate descriptor analysis. Five new derivatives of DTP (DH1-DH5) were designed through targeted control of terminal triphenylamine (TPA) units to rationally tune charge-transfer behavior, electronic structure, and interfacial properties. Among all candidates, DH1 shows favorable calculated charge-transport characteristics within the studied series, exhibiting a distinct combination of low hole reorganization energy (λ_h = 0.0115 eV), the highest hole-hopping rate (2.13 × 10¹⁵ s^-1), enabling good charge transport. DH1 also exhibits a stabilized LUMO energy (- 3.04 eV) and a smaller band gap (1.66 eV), facilitating effective intramolecular charge transfer (ICT) and enhanced optical absorption at 599 nm. It also exhibits the highest calculated dipole moment (21.68 D), indicating pronounced molecular polarity and electronic asymmetry; however, the implications of this polarity for solid-state interfaces and film formation require further investigation. Notably, structure-property relationships within the molecular series were revealed using data-driven methods, including principal component analysis, correlation mapping, and clustering. The analysis identifies LUMO energy, dipole moment, and band gap as useful descriptors of charge-transfer efficiency and optoelectronic performance and places DH1 in a distinct region of the calculated descriptor space within this studied series. This multivariate analysis provides a descriptive view of the relationships among the calculated molecular descriptors. Combining quantum-chemical calculations with multivariate statistical analysis can provide complementary molecular-level insights for the screening and design of HTMs. The results provide molecular-level insights into DH1-DH5 and offer a useful approach for guiding the future design and investigation of HTMs for PSC applications.

Density functional theory (DFT) calculations were used to investigate the structural, electronic, optical, charge-transfer, and interfacial properties of the designed DTP derivatives (DH1-DH5). Data-assisted descriptor analysis was subsequently performed using multivariate statistical techniques, including principal component analysis, correlation mapping, and clustering, to identify structure-property relationships and the descriptors most strongly associated with charge-transfer efficiency and optoelectronic performance.