Intermediate Phase‐Assisted Sequential Deposition Toward 15.24%‐Efficiency Carbon‐Electrode Cspbi₂br Perovskite Solar Cells

Abstract

All‐inorganic perovskite CsPbI2Br is emerging as a promising absorber material for perovskite solar cells (PSCs) due to its superior photophysical properties and thermal stability. However, there are still many great challenges to obtaining high‐quality, phase‐stable, thick CsPbI2Br films in ambient air to promote further development of the PSCs. Herein, for the first time, an intermediate phase‐assisted sequential deposition for desired CsPbI2Br films is proposed. It is carried out by sequentially spin‐coating PbBr2 and CsI precursors onto the substrate in ambient air, during which a Ruddlesden–Popper (R–P) perovskite intermediate phase film composed of a Cs‐Pb‐I‐Br complex is produced. After annealing, the intermediate phase film is transformed into a CsPbI2Br film consisting of CsPbI2Br grains and CsBr species through a spinodal decomposition reaction. The as‐obtained CsPbI2Br film holds full coverage, micro‐sized grains, and excellent phase stability. Moreover, the CsBr species located at grain boundaries can effectively passivate the defects. Therefore, a carbon‐electrode PSC with such a desired CsPbI2Br film yields the optimized efficiency of 15.24%, coupled with a remarkable photovoltage of 1.312 V and excellent stability in ambient air with relative humidity of 60–70%. The efficiency achieved herein is among the record efficiencies for carbon‐electrode PSCs based on various all‐inorganic perovskites reported currently.

Forming a composite electron blocking layer to enhance the performance of carbon-based CsPbI3 perovskite solar cells

“…In order to address the issue, researchers have introduced inorganic perovskites to replace the organic-inorganic hybrid perovskites as light absorbers in C-PSCs. [20][21][22][23][24][25] Among various inorganic perovskites, CsPbI 3 has shown great prospects duo to the suitable bandgap of 1.73 eV. [26][27][28][29][30][31][32] So far, great progress has been made on CsPbI 3 C-PSCs and over 16% PCE has been achieved.…”

Recent Progress of Film Fabrication Process for Carbon-Based All-Inorganic Perovskite Solar Cells

“…The two-step solution process can precisely control the growth process of CsPbI 2 Br films, which has great potential for fabricating higher performance C-IPSC-based CsPbI 2 Br. Our team adopted the two-step solution process to form a precursor film composed of Cs-Pb-Br complex, which was finally transformed into CsPbI 2 Br films containing CsBr by annealing (as shown in Figure 8a) [121]. In the second spin-coating process, water was innovatively used as the solvent for CsI, and the dose of CsI/H 2 O was optimized to 105 µL, which resulted in CsPbI 2 Br films with high crystallinity and large grain sizes were achieved, as indicated by the SEM images and XRD patters (Figure 8b-e).…”

Carbon-Based CsPbI3 Perovskite Solar Cells

“…By employing CsPbI 3-x Br x as light absorbers in C-PSCs, the light absorption range was extended and the short-circuit current density (Jsc) was improved. As a result, the champion PCE of 12.05% [11] and 15.24% [12] were achieved by CsPbIBr 2 and CsPbI 2 Br C-PSCs, respectively.…”