Crystallization Enhancement and Ionic Defect Passivation in Wide‐Bandgap Perovskite for Efficient and Stable All‐Perovskite Tandem Solar Cells

Abstract

By integrating wide‐bandgap (WBG) and narrow‐bandgap perovskites, monolithic all‐perovskite tandem solar cells have garnered significant attention as a prospective strategy for surpassing the efficiency limits of single‐junction cells. However, the WBG subcells, which significantly impact the performance and operational stability of all‐perovskite tandem solar cells, face notable challenges associated with pronounced nonradiative recombination losses and limited film photostability. Here, an efficient method is reported by adding potassium hypophosphite into the perovskite precursor solution to simultaneously regulate crystallization and passivate ionic defects in WBG perovskites. This approach results in high‐quality perovskite films and significantly improves the performance and photostability of WBG perovskite solar cells. The single‐junction devices with a 1.79 eV bandgap achieve a champion power conversion efficiency (PCE) of 20.06% with an open‐circuit voltage of 1.32 V. The devices retain ≈96% of their initial PCE following 913 h of continuous AM 1.5 G illumination. With these WBG perovskite subcells, monolithic all‐perovskite tandem solar cells are fabricated with an efficiency of 26.08%.

Suppressed Defects by Functional Thermally Cross‐Linked Fullerene for High‐Efficiency Tin‐Lead Perovskite Solar Cells

“…The higher built-in electric field in the C-PCBSD-based devices indicates more efficient charge extraction and collection. [39] Dark J-V curves and electrochemical impedance spectroscopy (EIS) are used to analyze the carrier recombination behaviors of the PSCs to understand the influence of C-PCBSD on charge carrier dynamics. C-PCBSD devices exhibit lower dark current density than control devices as shown in Figure S11 (Supporting Information).…”

Recent Progress of Wide Bandgap Perovskites towards Two-Terminal Perovskite/Silicon Tandem Solar Cells

“…Furthermore, the introduction of KI could effectively reduce halide migration, improve crystal quality, and prolong carrier lifetime. By incorporating potassium hypophosphite into the perovskite precursor solution, Qiao et al achieved an ultra-high V oc of 1.32 V and a champion PCE of 20.06% by simultaneously adjusting the crystalline and passivating ion defects [ 65 ].…”

“…Furthermore, the introduction of KI could effectively reduce halide migration, improve crystal quality, and prolong carrier lifetime. By incorporating potassium hypophosphite into the perovskite precursor solution, Qiao et al achieved an ultra-high V oc of 1.32 V and a champion PCE of 20.06% by simultaneously adjusting the crystalline and passivating ion defects [65]. Several chlorine-containing additives, including ammonium chloride and methylammonium chloride, have also been utilized in precursors to improve the crystallinity of perovskites [66].…”

Titanium Silicide: A Promising Candidate of Recombination Layer for Perovskite/Tunnel Oxide Passivated Contact Silicon Two-Terminal Tandem Solar Cells

“…29−36 In homojunctionbased tandem solar cells, TCO materials such as ITO and IZO have been widely employed as recombination layers. [29][30][31]37 In addition to the two aforementioned disadvantages of TCO, an additional TCO deposition process is required, which leads to high fabrication costs. Hence, the development of perovskite/ TOPCon tandem solar cells with a TCO-free recombination layer is necessary.…”