Date of this Version
Defect Passivation in Hybrid Perovskite Solar Cells by Zwitterions, Xiaopeng Zheng
The ionic defects on the surfaces and at the grain boundaries of organic-inorganic halide perovskite films are detrimental to the efficiency and stability of perovskite solar cells. In chapter 3, we showed that the zwitterions can effectively passivate ionic defects in several different types of hybrid perovskites with negatively and positively charged components. The efficient defect passivation reduces the charge-trap density and extends the carrier recombination lifetime- supported by calculating the density function. The defect passivation reduces the open-circuit-voltage deficit of the p-i-n structured device to 0.39 V and boosts the efficiency to a certified value of 20.59±0.45%. Moreover, the defect healing also significantly enhances the stability of films in ambient conditions. Our findings provide an avenue for defect passivation to further improve the efficiency and stability of solar cells.
The uniform and high-electronic-quality of perovskite thin films are essential for high-performance perovskite devices. Here, it was shown that the 3-[Dodecyl(dimethyl)ammonio]-1-propanesulfonate inner salt (DPSI), which is a zwitterionic lead (II)-coordination long chain molecule, plays dual roles in tuning the crystallization behavior and passivating defects of perovskites. The synergistic effect of crystallization control and defect passivation remarkably suppresses the pin-hole formation, reduces the charge trap density, and elongates the carrier recombination lifetime, boosting the planar perovskite device efficiency to 21.1%. Our findings provide an avenue for simultaneous crystallization control and defect passivation to further improve the performance of perovskite devices.
Advisors: Jinsong Huang and Jeffrey Shield