Enhanced Photovoltaic Performance of FASnI₃-Based Perovskite Solar Cells with Hydrazinium Chloride Coadditive

Synergy Effect of Both 2,2,2‐Trifluoroethylamine Hydrochloride and SnF2 for Highly Stable FASnI3−xClx Perovskite Solar Cells

“…According to the absorption spectra (Figure e) and the corresponding Tauc plots (Figure S3a, Supporting Information), the bandgaps of the two kinds of perovskite films are calculated as 1.30 and 1.36 eV, which is consistent with the previous report . Consistent with the band gap increase with the incorporation of Cl deduced from the absorption spectra, an obvious shift in the photoluminescence (PL) spectra from 946 to 911 nm can also be observed with the capsulation with glass and thermoplastic sealant, while the PL peaks of both control and optimal FASnI 3−x Cl x films without capsulation are vulnerable to the moisture and oxygen in air, shown in Figure S4, Supporting Information.…”

“…Grain size increases as TFEACl concentration increases, which can be attributed to the incorporation of Cl. The chloride ion successfully tuned the rate of chemical reaction of perovskite formation and assisted to form optimized film with larger grains, consistent with previous report . In addition, the brighter nanostructures observed in the control film likely originate from excess SnF 2 .…”

“…A variety of different additives have been reported to date, including various organic ammonium iodides, SnF 2 , and various reducing agents . The addition of SnF 2 , alone or combined with other additives, is a common approach to inhibit the formation of Sn 4+ and improve the film morphology. In the deposition of a tin‐based perovskite, SnF 2 additive affects the film nucleation by providing additional nucleation sites and enabling the formation of a more uniform film with high coverage .…”

Efficient and Stable FASnI3 Perovskite Solar Cells with Effective Interface Modulation by Low‐Dimensional Perovskite Layer

“…As shown in Figure 5a,t he work functions (f)o ft he FASnI 3 films withouta nd with PEABr treatment are calculated to be À5.10 and À4.80 eV,r espectively.A ccording to the tail of the UPS spectra in Figure 5b,t he corresponding valence-band maximum (VBM) valuesa re determined to be À5.44 and À5.30 eV,r espectively.D educed from the absorption spectra and the corresponding Tauc plots (Figure 5c and FigureS2i nt he Supporting Information), the band gaps of the FASnI 3 films without and with PEABr treatment are determined to be 1.34 and 1.40 eV,r espectively,c onsistent with the previousr eports. [9,30] When the low-dimensional ultrathin film was introduced after PEABr treatment, the film had a stronger PL intensity with ac lear blueshift to approximately 885 nm, whichc an be attributed to the enhanced crystallinity and band-gap increaseb yi ncorporation of Br and the formation of the low-dimensional PEA-based perovskite phase with larger band gap. The PL peak of the 3D FASnI 3 film is around 924 nm, consistentw ith the absorption results and previous reports.…”

“…[9,30] When the low-dimensional ultrathin film was introduced after PEABr treatment, the film had a stronger PL intensity with ac lear blueshift to approximately 885 nm, whichc an be attributed to the enhanced crystallinity and band-gap increaseb yi ncorporation of Br and the formation of the low-dimensional PEA-based perovskite phase with larger band gap. [30] Ac ombination of BCP ( % 5nm), Al ( % 5nm), andA g(% 80 nm) was utilized as the rear electrode in the device. Typically,t he low-dimensional perovskite has ah igherV BM and slightly wider band gap than the pristine FASnI 3 perovskite.…”