A Novel Anion Doping for Stable CsPbI₂Br Perovskite Solar Cells with an Efficiency of 15.56% and an Open Circuit Voltage of 1.30 V

Abstract

The Cs‐based inorganic perovskite solar cells (PSCs), such as CsPbI2Br, have made a striking breakthrough with power conversion efficiency (PCE) over 16% and potential to be used as top cells for tandem devices. Herein, I− is partially replaced with the acetate anion (Ac−) in the CsPbI2Br framework, producing multiple benefits. The Ac− doping can change the morphology, electronic properties, and band structure of the host CsPbI2Br film. The obtained CsPbI2−x Br(Ac)x perovskite films present lower trap densities, longer carrier lifetimes, and fast charge transportation compared to the host CsPbI2Br films. Interestingly, the CsPbI2−x Br(Ac)x PSCs exhibit a maximum PCE of 15.56% and an ultrahigh open circuit voltage (Voc) of 1.30 V without sacrificing photocurrent. Notably, such a remarkable Voc is among the highest values of the previously reported CsPbI2Br PSCs, while the PCE far exceeds all of them. In addition, the obtained CsPbI2−x Br(Ac)x PSCs exhibit high reproducibility and good stability. The stable CsPbI2−x Br(Ac)x PSCs with high Voc and PCE are desirable for tandem solar cell applications.

Managing Phase Purities and Crystal Orientation for High‐Performance and Photostable Cesium Lead Halide Perovskite Solar Cells

“…The results for CsPbI 2.2 Br 0.8 and CsPbI 2.4 Br 0.6 are given in Figure S3, Supporting Information. Although there are literature reports of cubic ( α ) phase CsPbI 2.0 Br 1.0 perovskites, here, we show that in the range of compositions investigated via this processing route, the primary perovskite phase appears to be a distorted orthorhombic ( γ ‐phase) at room temperature . More importantly, CsPbI 1.8 Br 1.2 exhibits a pure γ ‐phase, and in the more I‐rich perovskites, there is a mixture of a γ ‐phase and a non‐perovskite δ ‐phase, whereas CsPbI 2.7 Br 0.3 exhibits a pure δ ‐phase.…”

“…With the decrease in bromide content and bandgap, the open‐circuit voltage ( V oc ) is reduced from 1261 mV (CsPbI 1.8 Br 1.2 ) to 1207 mV (CsPbI 2.0 Br 1.0 ) to 1166 mV (CsPbI 2.2 Br 0.8 ). Notably, with the CsPbI 1.8 Br 1.2 perovskite, we achieved among the highest reported V oc values and PCEs for inorganic perovskite solar cells with a wide bandgap . Although we might expect an increase in the photocurrent with more I‐rich compounds, the value of J sc is quite similar for all compositions.…”

“…An alternative strategy to achieve stability is through halide alloying with bromide in CsPbI 3 − x Br x compositions, which has the further advantage of optical bandgap tenability across a range of phase‐stable perovskite compositions (in an inert atmosphere at room temperature) . Indeed, many works on CsPbI 2 Br perovskite have shown significant progress with the photovoltaic performance …”

Structurally Reinforced All‐Inorganic CsPbI2Br Perovskite by Nonionic Polymer via Coordination and Hydrogen Bonds

“…The prolonged charge recombination lifetime strongly indicates that PEI modification can effectively restrain charge recombination in CsPbI 2 Br–PEI‐based devices. [ 21 ]…”

Multilayer Cascade Charge Transport Layer for High‐Performance Inverted Mesoscopic All‐Inorganic and Hybrid Wide‐Bandgap Perovskite Solar Cells

“…In addition, a shift to higher binding energy can be revealed for Cs 3 d , Pb 4 f , I 3 d , and Br 3 d in their high‐resolution spectra compared with the pristine sample (Figure S6, Supporting Information), which should be attributed to the enhanced chemical bonding. [ 47,48 ]…”