F-Type Pseudo-Halide Anions for High-Efficiency and Stable Wide-Band-Gap Inverted Perovskite Solar Cells with Fill Factor Exceeding 84%

Abstract

The quality of wide-band-gap (WBG) perovskite films plays an important role in tandem solar cells. Therefore, it is necessary to improve the performance of WBG perovskite films for the development of tandem solar cells. Here, we employ F-type pseudo-halogen additives (PF6 – or BF4 –) into perovskite precursors. The perovskite films with F-type pseudo-halogen additives have a larger grain size and higher crystal quality with lower defect density. At the same time, the perovskite lattice increases due to substitution of F-type pseudo-halogen anions for I–/Br–, and the stress distortion in the film is released, which effectively suppresses the recombination of carriers, reduces the charge transfer loss, and inhibits the phase separation. Finally, the power conversion efficiency (PCE) of the inverted 1.67 eV perovskite devices is significantly improved to over 20% with an impressive fill factor of 84.02% and excellent device stability. In addition, the PCE of the four-terminal (4T) perovskite/silicon tandem solar cells reached 27.35% (PF6 –) and 27.11% (BF4 –), respectively. This provides important guidance for further improving WBG perovskite solar cell performance.

Dopamine Hydrochloride-Assisted Synergistic Modulation of Perovskite Crystallization and Sn2+ Oxidation for Efficient and Stable Lead-free Solar Cells

“…The presence of phase separation can be determined by the peak positions of the steady-state PL spectra (Figure S9). The peak position of the PL spectrum for DACl-derived perovskite film is the same as that of control films, indicating that 1% DACl should not lead to phase separation. However, the peak position shows a significant blue-shift for the perovskite films with 5% DACl, leading to phase separation of the perovskite film.…”

Simultaneous Surface Modification and Defect Passivation on Tin Oxide–Perovskite Interfaces using Pseudohalide Salt of Sodium Tetrafluoroborate

“…Fluorinated pseudohalogen anions can interact with Pb 2þ , MA þ , FA þ , and Cs þ species and/or replace iodine vacancies in a perovskite structure, causing a change in its lattice crystal. [41,42] We investigated the interaction, if any, between NaBF 4 and polycrystalline PbI 2 and FAI samples because these two constituents mainly compose our perovskite film. Figure 5d shows the Raman spectra of polycrystalline PbI 2 before and after NaBF 4 treatment.…”

Multifunctional Passivator Trifluoroacetamidine for Improving the Performance of All‐Inorganic CsPbI3 Perovskite Solar Cells

“…In addition, the larger grain size and denser morphology of the film facilitate the performance and stability of the device. [ 33 ] UV–vis absorption spectra were conducted for further exploring the photovoltaic characteristics in CsPbI 3 films with the addition of TFA. As shown in Figure 1d, the control CsPbI 3 film doped by 0.3 mol% TFA has a higher absorption edge and greater intensity before 700 nm.…”