Acetic Acid‐Assisted Synergistic Modulation of Crystallization Kinetics and Inhibition of Sn²⁺ Oxidation in Tin‐Based Perovskite Solar Cells

Abstract

Tin‐based halide perovskites attract incremental attention due to the favorable optoelectronic properties and ideal bandgaps. However, the poor crystalline quality is still the biggest challenge for further progress in tin‐based perovskite solar cells (PVSCs) due to the unfavorable defects and uncontrollable crystallization kinetics. Here, acetic acid (HAc) is first introduced to reduce the supersaturated concentration of the precursor solution to preferentially form pre‐nucleation clusters, thus inducing rapid nucleation for effective regulation of crystallization kinetics. In particular, the hydrogen ion and acetate ion contained in HAc can effectively inhibit the oxidation of Sn2+, and the hydrogen bonding interaction between HAc and iodide ion (I‐) greatly reduces the loss of I‐, which guarantees the I‐/Sn2+ stoichiometric ratio of the corresponding perovskite film close to theoretical value, thus effectively reducing the defect density and maintaining the perfect crystal lattice. Consequently, the HAc‐assisted tin‐based PVSCs achieve a champion power conversion efficiency of 12.26% with superior open‐circuit voltage up to 0.75 V. Moreover, the unencapsulated device maintains nearly 90% of the initial PCE even after 3000 h storage in nitrogen atmosphere. This demonstrated strategy enables to prepare high‐quality tin‐based perovskite film with lower defect density and lattice distortion.

Efficient Flexible Perovskite Solar Cells with Reduced Hysteresis Employing Cobalt Nitrate Treated SnO2

“…The V OC follows a liner relationship versus the logarithmic light intensity according to , where k B is the Boltzmann constant, T is the temperature, q is an elementary charge, and n is the ideal factor. [ 45 ] As shown in Figure 5b, n is calculated to be 1.59 and 1.85 kT q −1 for Co–SnO 2 and pristine SnO 2 ‐based flexible PSCs, respectively, which proves that trap assist recombination has been reduced. The J SC follows a linear relationship of I α , and the fitting values of α is 0.996 and 0.977 for flexible PSCs based on Co–SnO 2 and pristine SnO 2 , respectively, as shown in Figure S20a, Supporting Information.…”

“…Boltzmann constant, T is the temperature, q is an elementary charge, and n is the ideal factor. [45] As shown in Figure 5b, n is calculated to be 1.59 and 1.85 kT q À1 for Co-SnO Generally, the high-frequency component is related to the charge transfer resistance (R ct ), and the low-frequency component corresponds to the charge recombination resistance (R rec ) occurring at the interface. [24,46] As shown in Figure 5c, Co-SnO 2 -based device shows a smaller R ct and a larger R rec compared to the pristine SnO 2 -based one, indicating the reduced transfer resistance and increased recombination resistance.…”

Resolving Mixed Intermediate Phases in Methylammonium-Free Sn–Pb Alloyed Perovskites for High-Performance Solar Cells

“…The center of the DLS peak shifted from 4.5 to 76.1 nm after the addition of D-HLH. The presence of larger colloids implied that pre-nucleation clusters had formed in the D-HLH-treated perovskite precursor solution [ 47 , 48 ]. These clusters could decrease the energy barrier for nucleation during the precipitation process [ 49 , 50 ].…”

“…S3), the positive dipoles are buried inside the molecules of DMF and DMSO, whereas that of D-HLH is exposed externally. As a result, D-HLH can solvate anions more readily [ 48 ]. Moreover, the polar amino group (N δ– –H δ+ ) of D-HLH and the electronegative iodide ion (I δ– ) can form a hydrogen bond (–N–H···I – ).…”

Efficient Surface‐Defect Passivation by Sulfurous‐Acyl‐Included Small Molecule for High‐Performance Perovskite Photovoltaics

“…The longer lifetime reveals that it is more convenient for carriers to transport for a longer distances due to decreased defects, which is in agreement with the t DOS. Furthermore, the dark saturation–current curves were plotted to evaluate the shunt of charge carriers, [ 45 ] as shown in Figure 4c. Apparently, the optimized PSC devices are equipped with lower leakage current, testifying the decreased trap density.…”