Synergistic Benefits of Cesium‐Doped Aqueous Precursor in Air‐Processed Inverted Perovskite Solar Cells

Abstract

Air‐processed perovskite solar cells (PSCs) allay the need for costly fabrication in a controlled atmosphere but currently suffer from disadvantages in power conversion efficiency (PCE) and device stability. Herein, the systematic investigation into CH3NH3PbI3–xClx prepared with an antisolvent‐assisted process in a relative humidity of 40 ± 5% is reported, using cesium‐containing aqueous solutions of various strengths. Diffractometry and microscopy reveal how grain sizes vary among the samples, suggesting an optimum concentration for grain size. Those films are fabricated in air into solar cells, and their electrochemical impedance and current–voltage characteristics under light are measured. The films demonstrating optimum strength achieve PCEs of up to 16.6%, compared with the maximum of 14.4% achieved by untreated films. The air‐processed films also exhibit mitigated hysteresis, with indices decreasing to 0.021. Photoluminescence characterization reveals reduced defect densities in Cs‐doped materials and, together with photoelectron spectroscopy, suggests an upward shift in energy bands. Such changes explain the improvement in photovoltaic performance. Stability tests on unencapsulated cells over 14 days show that those made from the perovskite with optimum Cs‐doping degrade slowest, with their conversion efficiencies falling by <10% every 100 h. Our findings may contribute to the low‐cost commercialization of PSCs.

Improving the Electrical Properties and Hole Extraction Efficiency of Inverted Perovskite Solar Cells with AuCl3 Interfacial Modification Layer

“…This result is consistent with previous reports. [ 41 ] All perovskite films were formed under the same conditions, so the intensity of the diffraction peak in XRD corresponds to the crystallinity of perovskite. After the AuCl 3 ‐modified PEDOT:PSS, the intensity of (110), (220), and (310) diffraction peak of perovskite increased.…”

Efficient and Stable Inverted Perovskite Solar Cell using Potassium Fluoroborate Doped PEDOT:PSS

“…[28] The enhanced optical absorption of the perovskite film can be attributed to the larger grain size and better crystallinity of the perovskite grown on the film. [20,21,28,29] Increased optical absorption leads to the generation of more electron-hole pairs in the perovskite, contributing to improved performance of perovskite solar cells.…”

A review on advances in doping with alkali metals in halide perovskite materials

“…It is now well established from a variety of studies [52][53][54][55][56] that the doping of Cs ions into MAPbX 3 perovskites optimizes the optical and electrical parameters of the materials while retaining their fundamental properties. Guangcheng and Rui claimed that doping of Cs into the MAPbI 3-x Cl x perovskite films enhances the grain morphology, lifts the valence and conduction band edges, passivate the trap states, and hence promote the flow of charge carriers [57].…”