Theoretical and Experimental Investigation of Triphenylamine-Containing Hole Transport Materials with Side-Chain Isomerization.

contextIn perovskite solar cells (PSCs), hole transport materials (HTMs) are crucial for charge extraction and transport. Therefore, molecular design of HTMs is an effective method to enhance PSCs performance. Considering that triphenylamine is a common group for constructing HTMs, molecules PD-Cz and MD-Cz were designed based on a carbazole-diphenylamine backbone with isomeric triphenylamine. Density functional theory (DFT), molecular dynamics (MD) simulations, and Marcus theory were employed to study the geometric structures, photoelectric properties, and hole transport properties of the designed HTMs. Simulated results indicate that differences in intermolecular interactions lead to a higher hole mobility in PD-Cz than that of MD-Cz. After synthesizing PD-Cz and MD-Cz and applying them to PSCs, it was found that PD-Cz exhibits higher hole mobility, good film-forming ability, and excellent capability to inhibit electron-hole recombination. Consequently, under the same conditions, the PCE of PSC devices based on PD-Cz reached 23.05%, which is higher than the PCE of MD-Cz (19.50%). The mutual confirmation of experimental results and theoretical models demonstrates that model by employing a side-chain triphenylamine isomerization strategy in this work is expected to provide guidance for designing novel HTMs.

methodsDFT and TD-DFT calculations were carried out by the Gaussian 09. The ground-state geometry for the investigated molecules were optimized using the B3P86/6-311G(d, p) functional and basis set. The optical properties of the investigated molecules were calculated by TD-PBE0/6-31G(d) functional and basis set in dichloromethane solution with a polarizable continuum model (PCM). The MD simulations for the investigated molecules were conducted using the Gromacs program. Throughout the entire simulation process, the General Amber Force Field (GAFF) for HTMs and Universal Force Field (UFF) for perovskite was employed. The site energies, charge transfer integrals and overlap integrals were simulated at the PW91/TZP level using the ADF program.