Highly‐Stable CsPbI₃ Perovskite Solar Cells with an Efficiency of 21.11% via Fluorinated 4‐Amino‐Benzoate Cesium Bifacial Passivation

Abstract

The poor interface quality between cesium lead triiodide (CsPbI3) perovskite and the electron transport layer limits the stability and efficiency of CsPbI3 perovskite solar cells (PSCs). Herein, a 4‐amino‐2,3,5,6‐tetrafluorobenzoate cesium (ATFC) is designed as a bifacial defect passivator to tailor the perovskite/TiO2 interface. The comprehensive experiments demonstrate that ATFC can not only optimize the conductivity, electron mobility, and energy band structure of the TiO2 layer by passivation of the undercoordinated Ti4+, oxygen vacancy (VO), and free OH defects but also promote the yield of high‐quality CsPbI3 film by synergistic passivation of undercoordinated Pb2+ defects with the CO group and F atom, and limiting I− migration via F···I interaction. Benefiting from the above interactions, the ATFC‐modified CsPbI3 device yields a champion power conversion efficiency (PCE) of 21.11% and an excellent open‐circuit voltage (VOC) of 1.24 V. Meanwhile, the optimized CsPbI3 PSC maintains 92.74% of its initial efficiency after aging 800 h in air atmosphere, and has almost no efficiency attenuation after tracking at maximum power point for 350 h.

Interfacial modification between NiOx and perovskite layers with hexafluorophosphate salts for enhancing device efficiency and stability of perovskite solar cells

“…8b depicts the relationship between V OC and light intensity, revealing that the slope of the three salt-modified NiO x devices is higher than that of the controlled one. According to the previous literature, 46,47 the relationship between V OC and light intensity can be described by eqn (2):where n is the ideality factor, K is Boltzmann's constant, T is the absolute temperature, q is the elementary charge, J SC is the photo-generated current density, and J 0 is the dark saturation current. As evident in the V OC –light intensity relation, the ideality factor n typically denotes the dominant recombination mechanism in solar cells.…”

“…8b depicts the relationship between V OC and light intensity, revealing that the slope of the three salt-modified NiO x devices is higher than that of the controlled one. According to the previous literature, 46,47 the relationship between V OC and light intensity can be described by eqn (2):…”

Improving crystallization and photoelectric performance of CsPbI₂Br perovskite under ambient air via dynamic hot-air assisted recrystallization strategy

“…近年来, 有机无机杂化钙钛矿太阳能电池在光 伏领域展现出优异的光电转换效率(power conversion efficiency, PCE), 引起了研究者的广泛关 注 [1][2][3] . 然而, 有机无机杂化钙钛矿中的有机阳离 子 如 甲 胺 基 团 或 甲 脒 基 团 (methylamine, MA + ; formamidine, FA + )在高温下极易与氧或水反应, 导致钙钛矿结构最终分解为有机气体和碘化铅 [4] . 为了克服有机阳离子的不稳定性问题, 研究者转 向到耐热的全无机CsPbX 3 (X为Cl, Br, I或混 合 卤 素 )钙 钛 矿 的 研 究 [5][6][7] .…”

Healing the Buried Interface by a Plant-Derived Green Passivator for Carbon-Based CsPbIBr2 Perovskite Solar Cells

“…Although the efficiency of CsPbI 3 -based PSCs has exceeded 20%, the phase instability, which suffers from the phase conversion from the photoactive α-perovskite phase to the nonphotoactive βperovskite phase, is still a great challenge for future deployment. 11,19,20 On the contrary, CsPbBr 3 exhibits the most superior stability, but its PCE is restricted by a narrower light-absorbing range. 21 By balancing the stability and efficiency, the air-stable CsPbIBr 2 perovskite with a suitable bandgap (E g = 2.10 eV) is regarded as one potential material in practical application for tandem photovoltaics.…”

“…Organic–inorganic hybrid perovskite solar cells (PSCs) have attracted extensive attention due to their unique semiconductor properties, such as long charge carrier diffusion length, tunable bandgap, high defect tolerance, and low exciton binding energies. − Within a very short time span, impressive achievements in photovoltaic applications have been made, and the certificated power conversion efficiency (PCE) of single-junction PSCs has been rapidly increased to 26.1%, which is comparable to that of Si-based solar cells. − However, the poor long-term operational stability still restricts their practical application, largely because of the usage of humidity-/heat-sensitive organic methylammonium and formamidinium. − Substituting organic cations with volatile-free Cs + to fabricate all-inorganic perovskites (CsPbX 3 , X = I, Br, Cl, or mixed) is an effective strategy to settle this issue. , Generally, there is a positive correlation between I doge and corresponding PCE owing to the reduced bandgap but a negative relationship for environmental stability. Although the efficiency of CsPbI 3 -based PSCs has exceeded 20%, the phase instability, which suffers from the phase conversion from the photoactive α-perovskite phase to the nonphotoactive β-perovskite phase, is still a great challenge for future deployment. ,, On the contrary, CsPbBr 3 exhibits the most superior stability, but its PCE is restricted by a narrower light-absorbing range . By balancing the stability and efficiency, the air-stable CsPbIBr 2 perovskite with a suitable bandgap ( E g = 2.10 eV) is regarded as one potential material in practical application for tandem photovoltaics. , …”