2023 CEJ : PSCs Efficiency Reaches 22.9%! How All-In-One Additives Adjust Crystallization and Passivation
- The sulfonyl group and pyridine nitrogen synergistically passivate lead defects.
- Trifluoromethyl groups inhibit cation vacancies and improve humidity stability.
- Low dosage of organic additives realizes effective crystallization control.
- The 2-BTFSIP-modified MAPbI3 device yields a PCE of 21.96%, enhancement of ~15%.
In recent years, organic-inorganic metal halide perovskite solar cells (PSCs) have been considered as the third-generation photovoltaic devices with great application potential due to their rapidly increasing photoelectric conversion efficiency. However, currently widely used solution processing methods easily form perovskite films with small crystal size and high density of defect states, which directly affect the photoelectric conversion efficiency and stability of the device.
A study published in CEJ in January 2023, the research team use an all-in-one additive, named 2-[N,N-bi(trifluoromethylsulfonyl)amino]pyridine (2-BTFSIP), is introduced into the perovskite layer to address this issue. It is demonstrated that the sulfonyl group and pyridine nitrogen cooperatively passivate the deep-level traps (Pb0 cluster and under-coordinated Pb2+ ions), while the trifluoromethyl group suppresses the evaporation of organic cations as well as improves the hydrophobicity of perovskite films. In addition, crystallization control is also realized by the synergetic effect of multiple groups to obtain a larger crystal size. It is revealed that reduced defect densities, suppressed non-radiative recombination and prolonged carrier lifetimes are achieved.
Multifaceted Gains for Perovskite Photoactive Layers Based on “all-in-one” Additives. MAPbI3 and FAPbI3 devices passivated by the 2-BTFSIP molecule yield the champion power conversion efficiency (PCE) of 21.96% and 22.90% with negligible hysteresis, respectively. Meanwhile, 2-BTFSIP-modified MAPbI3 devices maintain over 90% of its original PCE as long as for 6000 h storage. Hence, this work provides a new perspective for designing effective multifunctional additives to remarkably improve PCE and stability of PSCs.
Fig. 1. Passivation mechanism of 2-BTFSIP molecule on MAPbI3 perovskite
Fig. 2. (a) J-V curves of MAPbI3 devices after several molecular modifications;
(b) EQE curves and corresponding integrated current density curves;
(c) steady-state PCE output at the maximum power point;
(d) Voc, Jsc, FF of the device and PCE parameter box plots.
Key word: Planar perovskite solar cells, Fluorinated organic molecules, Defect passivation,