Aryl Diammonium Iodide Passivation for Efficient and Stable Hybrid Organ‐Inorganic Perovskite Solar Cells

Abstract

Surface passivation is increasingly one of the most prominent strategies to promote the efficiency and stability of perovskite solar cells (PSCs). However, most passivation molecules hinder carrier extraction due to poorly conductive aggregation between perovskite surface and carrier transportation layer. Herein, a novel molecule: p-phenyl dimethylammonium iodide (PDMAI) with ammonium group on both terminals is introduced, and its passivation effect is systematically investigated. It is found that PDMAI can mitigate defects at the surface and promote carrier extraction from perovskite to the hole transporting layer, leading to a lift of open-circuit voltage of 40 mV. Profiting from superior PDMAI passivation, the average efficiency of PSCs has been elevated from 19.69% to 20.99%. As demonstrated with density functional theory calculations, PDMAI probably tends to anchor onto the perovskite surface with both NH 3 I tails, and enhances the adhesion and contact to perovskite layer. The exposed hydrophobic aryl core protects perovskite against detrimental environmental factors. In addition, the alkyl component between aryl and ammonium groups is demonstrated to be essentially vital in triggering passivation function, which offers the guidance for the design of passivation molecules.

Review of Interface Passivation of Perovskite Layer

“…A perovskite film prepared using a general solution method contains a large number of grain boundaries and defects such as dislocations, impurities, and vacancies owing to the fracture of chemical bonds that are easily formed at the grain boundaries [ 50 , 71 , 72 , 73 , 74 ]. The passivation of the grain boundary defects can effectively improve the efficiency and stability of PSCs [ 75 , 76 , 77 ]. Therefore, identifying a suitable passivation agent is essential for preparing efficient and stable PSCs.…”

Dually‐Passivated Perovskite Solar Cells with Reduced Voltage Loss and Increased Super Oxide Resistance

“…surface modification via coating functional molecules on the preformed perovskite layer. Various organic molecules [17–20] and polymers [21–24] have been applied to chemically passivate the defects on the perovskite surface in PSCs [25–27] . Albeit the success of the two methods, an optimal combination of them is needed to achieve maximized passivation effects for further improving efficiency and long‐term stability.…”

Passiviation of L-3-(4-Pyridyl)-alanine on Interfacial Defects of Perovskite Solar Cell

“…τ1、τ2 和平均寿命(τay)更长 [27] 。由于样品的衬底为玻 璃，不含电荷传输层，钙钛矿薄膜的荧光衰减与载 流子的非辐射复合密切相关，荧光寿命较长说明非 辐射复合被抑制， 导致 PLA 修饰样品的陷阱态密度 降低，有助于器件 FF 的提升。 图 6 PLA 修饰及参照玻璃/钙钛矿薄膜的(a)稳态 PL 光谱， 为定量表征 PLA 添加剂对钙钛矿薄膜陷阱态 密度的影响，本课题组制备了纯电子注入器件，其 结构为 FTO/TiO2/钙钛矿/PCBM/Au(图 7(a))，采用 SCLC 对器件进行测试 [28] 。器件测得的 I-V 曲线含 有三个不同的区域，分别为欧姆区域、子区域和陷 阱填充限制区域(TFL)，分别用红色、绿色和黄色线 段表示(图 7(b))。利用欧姆区到 TFL 区转折点处对 应的电压值(VTFL)和公式(2)可计算接近价带顶的陷 阱态密度 [29]…”