In Situ Stabilized CsPbI₃ for Air‐Fabricated Inverted Inorganic Perovskite Photovoltaics with Wide Humidity Operating Window

Abstract

Inverted triiodine cesium lead (CsPbI3) perovskite solar cells (PSCs) are promising in photovoltaics owing to their ideal light absorption, non‐volatile active layer, and avoidance of fragile Spiro‐OmeTAD, especially as the top cell in tandem devices. However, they still exhibit far‐lagging efficiency, and must be processed in a strictly controlled environment due to water‐fearing CsPbI3. Here, a novel strategy to convert the harmful water erosions into an in situ stabilizer for efficient inverted CsPbI3 PSCs fabricated with a wide humidity operating window, is proposed. During air fabrication, maleic anhydride (MAAD) can react with water molecules in air to reduce moisture erosions, while the hydrolysis products (maleic acid, MAAC) control grains growth. After annealing, MAAC strongly binds to CsPbI3 grains as a shield to hamper phase transition and moisture penetration. A champion efficiency of 19.25% is obtained, which is the highest efficiency among the inverted inorganic PSCs. In parallel, the authors’ optimized devices present efficiency of 18.39% even fabricated in relative humidity 60% condition. Moreover, the stability against various ages is improved, and the optimized devices remain at 96.8% of its initial efficiency after maximum power point tracking at 65 °C for 850 h.

Fluorinated Interfaces for Efficient and Stable Low‐Temperature Carbon‐Based CsPbI2Br Perovskite Solar Cells

“…A shorter τ tra and longer τ rec in KTFA and CF 3 PMABr-modified device further indicated that the suppressed charge recombination and the improved charge extraction efficiency due to the fewer defects. [63][64][65] Figure S29 (Supporting Information)shows the capacitance-voltage (C -2 -V) plots, from which the built-in potential (V bi ) can be calculated according to the Mott-Schottky equation. [3] Obviously, the KTFA & CF 3 PMABr modified device exhibited the largest V bi value compared to the other devices, which was consistent with the increased V oc value.…”

Tailoring Defects Regulation in Air-Fabricated CsPbI3 for Efficient Inverted All-Inorganic Perovskite Solar Cells with Voc of 1.225 V

“…3,5-Difluorobenzoic acid hydrazide (FBJ) was obtained from the Shanghai Macklin Biochemical Co., Ltd. All the raw materials are used without further treatment. The P3CT-N solution and PCBM (10 mg/mL in CB) were fabricated according to previous reports. , The CsPbI 3 perovskite precursor was obtained by dissolving 0.65 M CsI (170 mg), 0.65 M PbI 2 (300 mg), and 0.78 M DMAI (135 mg) in 1 mL of DMF solvent. The concentrations of FBJ and FPEAI additives in precursor are 4 and 2 mg/mL, respectively.…”

“…The UV–vis absorption spectra were obtained with the model HP8453. The high-resolution transmission electron microscope (HR-TEM) images of FBJ doped films (16 mg/mL) were conducted the same way as in the literature . SCLC curves were measured by the Keithley 2400 source meter.…”

“…The V I and Pb I traps would break up the balance between the neighboring [PbI 6 ] 4– octahedrons and would lower the free-energy barrier for phase transition of CsPbI 3 . ,− In parallel, these traps can also act as nonradiative centers to capture carriers and hamper their V oc improvement. Furthermore, the crystallization of the CsPbI 3 has been proved to be significantly influenced by the humidity during air operation, , which leaves the limitation of air-fabricated CsPbI 3 PSCs. Molecular passivation has been widely used to regulate the crystallization and minimize the traps in the air-fabricated CsPbI 3 films. ,− In particular, the organoamine halogen salts have played significant roles in the photovoltaic promotion of regular (n–i–p) CsPbI 3 PSCs as the surface termination, − additives, , and space cations of two-dimensional CsPbI 3 . − Despite the considerable promotions for air-fabricated regulation with the organoamine halogen salts, comprehensively suppressing defects formation from the external erosions is still a challenge for air-fabricated CsPbI 3 films, which might also be of significance to the air-fabricated inverted structures.…”

Organic Molecules in All‐Inorganic CsPbIxBr3−xPerovskite Solar Cells: Interface Modifiers or Precursor Additives

“…The maleic anhydride (MAAD) was employed to react with water molecules in the air to reduce moisture erosions, while the hydrolysis products (MAAc) regulate grain growth. [ 107 ] After annealing, MAAc strongly binds to CsPbI 3 grains as a shield to hamper phase transition and moisture penetration. A biureamide molecule combining amino (–NH 2 ) and carbonyl (–C=O) groups was selected as a novel additive to the CsPbI 2 Br perovskite precursor solution.…”