Simultaneous Defect Passivation and Electric Level Regulation with Rubidium Fluoride for High-Efficiency CsPbI₂Br Perovskite Solar Cells

Abstract

Due to the good balance of efficiency and stability, CsPbI 2 Br perovskite solar cells (PSCs) recently have attracted widespread attention. However, the improvement in photovoltaic performance for CsPbI 2 Br PSCs was mainly limited by massive defects and unmatched energy levels. Surface modification is the most convenient and effective strategy to decrease defect densities of perovskite films. Herein, we deposited rubidium fluoride (RbF) onto the surface of CsPbI 2 Br perovskite films by spin-coating. The numerous defects could be significantly passivated by RbF, resulting in suppressed nonradiative recombination. Furthermore, the CsPbI 2 Br perovskite film after RbF treatment exhibits a deeper Fermi level, and an additional built-in electric field forms to promote charge transport. Consequently, the champion device achieves a high efficiency of 10.82% with an improved V OC of 1.14 V, and it also exhibits excellent stability after long-term storage. This work offers a simple and effective approach to enhance the photovoltaic performance and stability of PSCs for broader applications in the future.

In Situ PL Tracking of Halide Exchange at 3D/QD Heterojunction Perovskite Solar Cells

“…The trPL analysis (see Figure f and Table S2) shows that the fast decay component observed in the first nanoseconds, commonly associated with surface trap-assisted recombination, exhibits an increase (from 1 to ∼18 ns) after passivation along with a decrease in its amplitude (from 78% to 47%). This trap-assisted recombination suppression, as well as the increase in the radiative slow decay component (and also its amplitude), significantly increases the carrier recombination lifetime of the bulk film (from 214.4 to 534.2 ns) . This is strong evidence that, during the halide exchange at the interface, the Br – originating from the QD can passivate the undercoordinated Pb 2+ (i.e., the halide vacancies) via a vacancy-mediated exchange mechanism and, consequently, reduce the nonradiative recombination pathways, increasing the PL intensity (detailed in the Supporting Information).…”

Exploration HTL-Free all inorganic mixed halide perovskite solar cells: effects of 4-ADPA passivation

“…Zhu et al deposited a layer of rubidium fluoride on the surface of CsPbI 2 Br using spin coating. This method enhanced charge carrier transport and reduced non-radiative recombination, resulting in the highest achieved PCE of 10.82% [57]. Yu et al have adopted 2,5-thiophene dicarboxylic acid to perform passivation at perovskite/carbon interface.…”