Spray‐Coated Lead‐Free Cs₂AgBiBr₆ Double Perovskite Solar Cells with High Open‐Circuit Voltage

Abstract

Lead‐free Cs2AgBiBr6 double perovskite is considered a promising alternative photovoltaic absorber to the widely used lead halide perovskite due to its easy processability, high stability, and reduced toxicity. Herein, for the first time spray processing for the deposition of Cs2AgBiBr6 double perovskite thin films is reported. Microstructural (X‐ray diffraction, scanning electron microscopy) and optoelectronic (absorbance, photoluminescence, photocurrent density versus applied voltage curves, electrochemical impedance spectroscopy) properties of spray‐coated film are compared with the spin‐coated benchmark. Incorporation of the spray‐coated Cs2AgBiBr6 double perovskite thin films in solar cells leads to a 2.3% photoconversion efficiency with high open‐circuit voltage of 1.09 V. This study highlights the suitability of ultrasonic spray deposition for the optimization of Cs2AgBiBr6 solar cells in terms of light absorption properties and charge transfer at the Cs2AgBiBr6/hole transporting layer interface.

Suppressing Interfacial Shunt Loss via Functional Polymer for Performance Improvement of Lead‐Free Cs2AgBiBr6 Double Perovskite Solar Cells

“…As shown in Figure 1c, the results are matchable to the J-V curves, which are also in accordance with the enhanced optical absorption of Cs 2 AgBiBr 6 perovskite films (Figure S2, Supporting Information). By carefully comparing the results with previously reported works, [21,34,45] the IPCE values for the control device are similar, an indicator of the considerable perovskite film with this solution-processable fabrication technology. Furthermore, the statistical distribution box diagram of the measured PCEs from random 12 PSCs with different PMMA concentrations is shown in Figure 1d.…”

Pulsed Laser Deposition of Cs2AgBiBr6: from Mechanochemically Synthesized Powders to Dry, Single-Step Deposition

“…Most reports on double perovskites have focused on nanocrystals 8−11 or solution-based processes where powders are obtained through a filtering and drying process. 12−14 Specifically for Cs 2 AgBiBr 6 , only few studies have shown thin films of double perovskites formed through the traditional spin-coating process, 3,15,16 where low solubility of precursors hampered the synthesis of dense, thick films. 15,17,18 In this respect, dry, vapor-based processes are preferred for Cs 2 AgBiBr 6 .…”

Cs2AgBiBr6 Double Perovskites as Lead‐Free Alternatives for Perovskite Solar Cells?

“…To ensure that no precursor traces or secondary phases such as Cs 3 Bi 2 Br 9 or Cs 2 AgBr or Cs 3 AgBr 2 are present in the thin films, postannealing of at least 250 C has to be applied. While the annealing temperature can be slightly reduced to 200 C by vacuum-assisted annealing beforehand, [54] other techniques such as laser assisted (at 200 C process temperature), [55] spray coating, [56] and vapor-assisted deposition [15,28,[57][58][59] demand for high annealing temperatures and yield power conversion efficiencies of only up to 1.41% in solar cells. The most commonly used technique, however, is spin coating during which the double perovskite solution (usually with concentrations of 0.5-0.6 M) is dropped quickly on a fastspinning substrate.…”