Pseudohalide Anions to Suppress Oxidative Degradation for Efficient Formamidinium-Based Sn–Pb Halide Perovskite Solar Cells,ACS Applied Materials & Interfaces

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Pseudohalide Anions to Suppress Oxidative Degradation for Efficient Formamidinium-Based Sn–Pb Halide Perovskite Solar Cells
ACS Applied Materials & Interfaces ( IF 8.3 ) Pub Date : 2022-04-12 , DOI: 10.1021/acsami.1c23949
Lian Wang ₁ , Zhongxiao Wang ₁ , Hui Li ₁ , Bohong Chang ₁ , Lu Pan ₁ , Zhirun Xie ₁ , Longwei Yin ₁

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Although binary Sn–Pb perovskites possess optimal band gap approaching to the Shockley–Queisser limit efficiency, the enhancement on power conversion efficiency (PCE) of Sn–Pb perovskite solar cells (PSCs) is impeded by the detrimental oxidation of Sn²⁺. Herein, a novel and effective strategy is developed to introduce pseudohalide anion thiocyanate (SCN^–) with similar ionic radius to iodide to occupy the X-site of the perovskite lattice, thus restraining the rapid oxidation of Sn²⁺ to Sn⁴⁺. The incorporation of SCN^– into perovskite stabilizes the perovskite crystal structure thermodynamically and increases the adsorption-energy-barrier of oxygen molecules. The coordination between Sn²⁺ and SCN^– can reduce the defect density by healing the undercoordinated Sn²⁺ and suppressing the Sn and I vacancies. With the incorporation of SCN^–, the ion migration behavior and lattice strain associated with the defects are remarkably relaxed. The study on carrier dynamics based on steady-state and time-resolved photoluminescence suggests that the carrier lifetime and non-radiative recombination rate of SCN^– PSCs can be remarkably prolonged and depressed, respectively. As a result, FASn_0.5Pb_0.5I₃-based PSCs achieve a 14.5% increase in PCE, reaching 13.74% under AM 1.5G illumination. This strategy takes a noteworthy step toward high efficiency and high stability FA-based Sn–Pb PSCs.

中文翻译：

拟卤化物阴离子抑制高效甲脒基 Sn-Pb 卤化物钙钛矿太阳能电池的氧化降解

尽管二元 Sn-Pb 钙钛矿具有接近 Shockley-Queisser 极限效率的最佳带隙，但 Sn-Pb 钙钛矿太阳能电池 (PSC) 的功率转换效率 (PCE) 的提高受到 Sn ²⁺的有害氧化的阻碍。本文开发了一种新颖有效的策略，引入离子半径与碘化物相似的拟卤化物阴离子硫氰酸盐（SCN-）占据钙钛矿晶格的X位，从而抑制Sn ²⁺快速^氧化为Sn ⁴⁺。将 SCN ^-掺入钙钛矿中可在热力学上稳定钙钛矿晶体结构并增加氧分子的吸附能垒。Sn ^{2+之间的配位}和 SCN ^–可以通过修复欠配位的 Sn ²⁺并抑制 Sn 和 I 空位来降低缺陷密度。随着 SCN ^-的掺入，与缺陷相关的离子迁移行为和晶格应变显着放松。基于稳态和时间分辨光致发光的载流子动力学研究表明，SCN ^- PSCs 的载流子寿命和非辐射复合率可以分别显着延长和降低。结果，FASn _0.5 Pb _0.5 I ₃基于 PSC 的 PCE 提高了 14.5%，在 AM 1.5G 照明下达到 13.74%。该策略朝着高效率和高稳定性的 FA 基 Sn-Pb PSC 迈出了值得注意的一步。

更新日期：2022-04-12

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