Ambient-Air-Stable Lead-Free CsSnI₃ Solar Cells with Greater than 7.5% Efficiency

Abstract

Black orthorhombic (B-γ) CsSnI3 with reduced biotoxicity and environmental impact and excellent optoelectronic properties is being considered as a promising eco-friendly candidate for high-performing perovskite solar cells (PSCs). A major challenge in a large-scale implementation of CsSnI3 PSCs includes the rapid transformation of Sn2+ to Sn4+ (within a few minutes) under an ambient-air condition. Here, we demonstrate that ambient-air stable B-γ CsSnI3 PSCs can be fabricated by incorporating N,N′-methylenebis­(acrylamide) (MBAA) into the perovskite layer and by using poly­(3-hexylthiophene) as the hole transporting material. The lone electron pairs of −NH and −CO units of MBAA are designed to form coordination bonding with Sn2+ in the B-γ CsSnI3, resulting in a reduced defect (Sn4+) density and better stability under multiple conditions for the perovskite light absorber. After a modification, the highest power conversion efficiency (PCE) of 7.50% is documented under an ambient-air condition for the unencapsulated CsSnI3-MBAA PSC. Furthermore, the MBAA-modified devices sustain 60.2%, 76.5%, and 58.4% of their initial PCEs after 1440 h of storage in an inert condition, after 120 h of storage in an ambient-air condition, and after 120 h of 1 Sun continuous illumination, respectively.

Over 8% efficient CsSnI3-based mesoporous perovskite solar cells enabled by two-step thermal annealing and surface cationic coordination dual treatment

“…Both resonance signals shifted positively to 168.5 and 182.8 ppm for SnI 2 –CPT and CsI–SnI 2 –CPT samples (the resonance signals of the SnI 2 –CPT sample were covered by those of the CsI–SnI 2 –CPT sample), verifying the appearance of the coordination interactions between Sn 2+ and the CO, CS functional groups of CPT. 34 We further conducted the FTIR measurements to acquire more details about the interaction between CPT and CsSnI 3 . The FTIR spectra of CPT, SnI 2 –CPT, and CsI–SnI 2 –CPT complex powder samples are shown in Fig.…”

Earth-abundant non-toxic perovskite nanocrystals for solution processed solar cells

“…63 The observed performance is very encouraging towards the development of lead-free inorganic solar cells. Indeed, the 12.96% efficiency obtained with CsSnI 3 QRs is the best result for non-toxic perovskite NCs reported to date, surpasses the efficiency obtained with bulk CsSnI 3 (7.5%), 48 and is very close to the efficiency delivered by analogous lead-perovskite NCs devices (16%).…”

“…For example, optimized all-inorganic CsSnI 3 solar cells have shown a 4.81% power conversion efficiency, 47 recently improved up to 7.5% by incorporating N,N 0 -methylenebis (acrylamide) into the perovskite layer. 48 FASnI 3 perovskite solar cells treated with SnF 2 -pyrazine showed an efficiency of 4.8%, maintained over 100 days, 49 which was later improved up to 9% when mixing the 3D FASnI 3 perovskite with a small quantity of the 2D Sn-perovskite PEA 2 SnI 4 (PEA = phenylethylammonium). Apparently, the addition of the 2D material promotes the growth of highly crystalline and oriented FASnI 3 grains which reduces the number of grain boundaries, suppresses tin vacancies, and improves charge carrier lifetime.…”

Advances in Tin(II)‐Based Perovskite Solar Cells: From Material Physics to Device Performance

“…Recently, Priya et al and Yin et al introduced N,N-methylenebis(acrylamide) (MBAA) and thiosemicarbazide (TSC) additives in all-inorganic CsSnI 3 PSCs and obtained a champion PCE of 7.50% and 8.20% (achieved the highest efficiency at that time) with outstanding stabilities (Figure 14c and d), respectively. [168,172] The excellent performance was mainly ascribed to the functional groups (ÀNH and ÀCO) in MBAA and S═C─N in TSC that have strong coordination with Sn 2þ or charge defects at GBs, thereby increasing electron density around defects and reducing defect densities (Figure 14e).…”

“…d,e) Reproduced with permission. [172] Copyright 2021, American Chemical Society. demonstrated that via modifying ETL (such as forming a cascaded structure), device performance can be enhanced for Sn-based PSCs.…”