近日，西安交通大学Zhaoxin Wu课题组与美国西北大学Mercouri G. Kanatzidis小组合作研究出更高效钙钛矿太阳能电池。 相关论文发表在2020年11月4日的《美国化学会志》上。

研究人员报告了从分子角度设计的一种新化学衍生物，采用新间隔阳离子3-苯基-2-丙烯胺(PPA)和共轭骨干作为低温策略组装更高效的太阳能电池。首先，该研究组使用X射线衍射解决和细化了通式为(PPA)₂(FA_0.5MA_0.5)_n1Pb_nI_3n+1 (n = 2和3，空间群C2)单晶的晶体结构，然后使用混合卤(PPA)₂(Cs_0.05(FA_0.88MA_0.12)_0.95)_n1Pb_n(I_0.88Br_0.12)_3n+1类似物来实现更高效的器件。

当形成RP相时，PPA与无机正八面体之间的多个氢键强化了分层结构。对于薄膜，该课题组观察到当目标层厚度指数从n = 2增加到n = 4，无机层的偏向水平的取向逐步减少，伴随着高n或者3D相出现的增加，并有更高的自由电荷载体流和垂直于基质电导率。因此，课题小组利用PPA-RP钙钛矿，实现了平面p–i–n太阳能电池14.76%的效率，封装后在85°C和85％的湿度下（ISOS-D-3 ）经过600 h，其效率仍保持93.8±0.25%。

据悉，卤化物钙钛矿Ruddlesden-Popper（RP）相是可溶液处理的半导体的一种同质层分层的子类，引起了极大的关注，特别是对于开发长期的太阳能光伏。他们的化学式定义为(A′)₂(A)_n-1Pb_nX_3n+1 (A′ = 间隔阳离子, A = 笼阴离子, X = 卤素粒子)。低温自组装薄膜的取向控制是与控制垂直于基质的电荷载流子传输能力相关的基本问题。

附：英文原文

Title: Alternative Organic Spacers for More Efficient Perovskite Solar Cells Containing Ruddlesden–Popper Phases

Author: Jun Xi, Ioannis Spanopoulos, Kijoon Bang, Jie Xu, Hua Dong, Yingguo Yang, Christos D. Malliakas, Justin M. Hoffman, Mercouri G. Kanatzidis, Zhaoxin Wu

Issue&Volume: November 4, 2020

Abstract: The halide perovskite Ruddlesden–Popper (RP) phases are a homologous layered subclass of solution-processable semiconductors that have aroused great attention, especially for developing long-term solar photovoltaics. They are defined as (A′)₂(A)_n-1Pb_nX_3n+1 (A′ = spacer cation, A = cage cation, and X = halide anion). The orientation control of low-temperature self-assembled thin films is a fundamental issue associated with the ability to control the charge carrier transport perpendicular to the substrate. Here we report new chemical derivatives designed from a molecular perspective using a novel spacer cation 3-phenyl-2-propenammonium (PPA) with conjugated backbone as a low-temperature strategy to assemble more efficient solar cells. First, we solved and refined the crystal structures of single crystals with the general formula (PPA)₂(FA_0.5MA_0.5)_n1Pb_nI_3n+1 (n = 2 and 3, space group C2) using X-ray diffraction and then used the mixed halide (PPA)₂(Cs_0.05(FA_0.88MA_0.12)_0.95)_n1Pb_n(I_0.88Br_0.12)_3n+1 analogues to achieve more efficient devices. While forming the RP phases, multiple hydrogen bonds between PPA and inorganic octahedra reinforce the layered structure. For films we observe that as the targeted layer thickness index increases from n = 2 to n = 4, a less horizontal preferred orientation of the inorganic layers is progressively realized along with an increased presence of high-n or 3D phases, with an improved flow of free charge carriers and vertical to substrate conductivity. Accordingly, we achieve an efficiency of 14.76% for planar p–i–n solar cells using PPA-RP perovskites, which retain 93.8 ± 0.25% efficiency with encapsulation after 600 h at 85 °C and 85% humidity (ISOS-D-3).

DOI: 10.1021/jacs.0c09647

Source: https://pubs.acs.org/doi/10.1021/jacs.0c09647