Molecular Interaction Modulates Crystallization and Defects of Perovskite Films for High-Performance Solar Cells

To modulate the crystallization and defects of perovskite grains, an organic small molecule, 9-(4-methoxyphenyl)-10-tosylphenanthrene (MPTP), is synthesized and introduced into the perovskite film. Different techniques (Fourier transform infrared spectroscopy, nuclear magnetic resonance, X-ray photoelectron spectroscopy) are used to reveal the hydrogen bonding and coordination interactions between MPTP and perovskite, which are also supported by density functional theory simulation. As a result, larger grains and reduced defects of perovskite films are obtained, along with lessened nonradiative recombination and enhanced hole extraction in resultant devices. The MPTP-treated devices show significantly improved efficiency from 20.9% to 23.04%, along with enhanced storage and thermal stability.