Star-Shaped Molecules as Dopant-Free Hole Transporting Materials for Efficient Perovskite Solar Cells: Multiscale Simulation.

On the reported TCP-OH (See Scheme 1), other two star-shaped molecules are theoretically designed by replacement of side group of TCP-OH by N,N-di(4-methoxyphenyl)aniline for TPAP-OH and oxygen-bridged triarylamine for TBOPP-OH. The core group, phenol, is kept in three molecules. Their potential to be hole transport material in perovskite solar cells without dopants is evaluated by multiscale simulations. The properties of isolated molecules are estimated by the frontier molecular orbital, absorption spectrum, and hole mobility. After that, the HTM@CH3 NH3 PbI3 adsorbed system is studied to consider the influence of adsorption on HTM performance. Besides the primary judgment, the glass transition temperature is also simulated to determine the stability of amorphous film. Not only the chemical stability is evaluated but also the amorphous film stability is considered. The latter is almost neglected in previous theoretical studies to evaluate the properties of HTMs. The performance of a designed molecule is evaluated from both the isolated molecules and HTM@CH3 NH3 PbI3 adsorbed system including aforementioned items, which is favorable to build reliable structure-property relationship.