Understanding the dopant induced effects on SFX-MeOTAD for perovskite solar cells: a spectroscopic and computational investigation
Understanding the dopant induced effects on SFX-MeOTAD for perovskite solar cells: a spectroscopic and computational investigation
复制标题
DOI：
10.1039/d1tc04172j
复制
发表时间：
2021-10-12
影响因子：
6.4
通讯作者：
Ivaturi, Aruna
中科院分区：
文献类型：
--
作者：
Gunn, Fraser;Ghosh, Paheli;Ivaturi, Aruna
SFX-MeO 2 [2，2 '，7，7'-四（N，N-二（4-甲氧基苯基）氨基）-螺-（芴-9，9 '-氧杂蒽）]（也称为X60）已成为钙钛矿太阳能电池中普遍存在但过于昂贵的螺-MeO 2空穴传输材料（HTM）的成本有效的替代品。使用其预氧化的双阳离子盐SFX-（TFSI）（2），已经进行了该HTM的受控浓度依赖性电导率调谐，而不需要空气（氧气）暴露。本研究详细介绍了这种低成本HTM的光学和电学性质的修改作为双阳离子盐的浓度（0-100摩尔%）的函数，使用紫外-可见吸收和电导率测量。用X射线吸收光谱和光电子能谱研究了双阳离子盐对SFX-MeO 2电子性质的增强作用。通过引入双阳离子SFX-（TFSI）（2），已经表明当使用20.5mol%的最佳掺杂剂浓度时，SFX-MeO 3的电导率从2.55 × 10（-8）S cm（-1）增加了4个数量级至9.4 × 10（-4）S cm（-1）。SFX-MeO 3的氧化程度通过UV-vis吸收测定，并使用计算计算进行合并。XPS研究表明，用SFX（TFSI）（2）掺杂SFX-MeO 3不仅导致HTM的氧化，而且还导致碳和氮周围的局部化学变化，这直接影响掺杂膜的导电性。NEXAFS研究表明，掺杂最初增强了分子的芳香性，但增加掺杂剂浓度进一步影响芳香性和可能的π堆叠，类似于SFX-MeOH 4膜的掺杂剂浓度依赖性电导率中所见的趋势。这些发现对基于三芳基胺的HTM的掺杂剂浓度和抗衡离子的选择具有影响。
SFX-MeOTAD [2,2 ',7,7 '-tetrakis(N,N-di(4-methoxyphenyl)amino)-spiro-(fluorene-9,9 '-xanthene)] (also known as X60) has emerged as a cost-effective alternative to the ubiquitous, but excessively-expensive, spiro-MeOTAD hole transport material (HTM) in perovskite solar cells. Using its pre-oxidised dicationic salt, SFX-(TFSI)(2), a controlled concentration dependent conductivity tuning of this HTM without the requirement of air (oxygen) exposure has been carried out. This study details the modifications in the optical and electrical properties of this low cost HTM as a function of the concentration of the dicationic salt (0-100 mol%) using UV-vis absorption and electrical conductivity measurements. X-ray absorption and photoelectron spectroscopy investigations have been carried out to elucidate the role of the dicationic salt in the enhanced electronic properties of SFX-MeOTAD. By incorporating the dicationic SFX-(TFSI)(2) it has been shown that the conductivity of SFX-MeOTAD increased by 4 orders of magnitude from 2.55 x 10(-8) S cm(-1) to 9.4 x 10(-4) S cm(-1) when using an optimal dopant concentration of 20.5 mol%. The degree of oxidation of SFX-MeOTAD was determined through UV-vis absorption and consolidated using the computational calculations. The XPS study reveals that doping SFX-MeOTAD with SFX(TFSI)(2) not only results in the oxidation of the HTM but also leads to a variation in the local chemistry around carbon and nitrogen which directly influences the conductivity of the doped films. NEXAFS studies indicate that doping enhances the aromatic nature of the molecule initially but increasing the dopant concentration further affects the aromaticity and possibly the pi stacking, similar to the trend seen in dopant concentration dependent conductivity of the SFX-MeOTAD films. These findings have implications on the choice of dopant concentration and counterions more generally for triarylamine based HTMs.