Effects of the Number of Bromine Substitution on Photovoltaic Efficiency and Energy Loss of Benzo[1,2‐b:4,5‐b′]diselenophene‐based Narrow‐Bandgap Multibrominated Nonfullerene Acceptors
Effects of the Number of Bromine Substitution on Photovoltaic Efficiency and Energy Loss of Benzo[1,2‐b:4,5‐b′]diselenophene‐based Narrow‐Bandgap Multibrominated Nonfullerene Acceptors
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DOI：
10.1002/solr.201800250
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发表时间：
2018-11
期刊：
影响因子：
7.9
通讯作者：
Shigang Wan;Chunmei Chang;Jin-liang Wang;Gui-Zhou Yuan;Qing Wu;Maojie Zhang;Yongfang Li
中科院分区：
文献类型：
--
作者：
Shigang Wan;Chunmei Chang;Jin-liang Wang;Gui-Zhou Yuan;Qing Wu;Maojie Zhang;Yongfang Li
在这项工作中，三种近红外（NIR）吸收非富勒烯小分子受体（NF-SMA）（BDSeIC，BDSeIC2Br和BDSeIC4Br）基于稠合苯并[1,2-b:4,5-b']二硒吩单元作为富电子中心核心和已经合成了具有或不具有一个或两个溴取代基作为缺电子基团的2-(2,3-二氢-3-氧代-1H-茚-1-亚基)丙二腈(INCN)，用于聚合物太阳能电池。与没有溴取代的BDSeIC相比，这些多溴化材料BDSeIC2Br和BDSeIC4Br表现出更低的能级、在500-900nm范围内更强的吸收、更好的晶体质量和增强的电子迁移率。以PM6为供体的最佳BDSeIC2Br基器件实现了高达12.5%的高功率转换效率（PCE）和0.52eV的相对较低的能量损失（Eloss）。基于BDSeIC2Br的器件的PCE为12.5％，远高于基于PM6：BDSeIC（7.1％）或PM6：BDSeIC4Br（9.6％）共混膜的器件，并且它是具有溴化INCN封端的NF-SMA的二元PSC中报道的最高PCE。 BDSeIC2Br基器件如此出色的PCE归因于更平衡的电子/空穴迁移率、更高的电荷离解和电荷收集效率以及更合适的相分离特性。这些结果表明，引入苯并[1,2-b:4,5-b']二硒吩核心单元和端基上的溴取代是实现高性能近红外吸收NF-SMA的有效方法。
In this work, three near‐infrared (NIR) absorption nonfullerene small‐molecule acceptors (NF‐SMAs) (BDSeIC,BDSeIC2Br, andBDSeIC4Br)based on a fused benzo[1,2‐b:4,5‐b′]diselenophene unit as the electron‐rich central core and 2‐(2,3‐dihydro‐3‐oxo‐1H‐inden‐1‐ylidene)propanedinitrile (INCN) without or with one or two bromine substituents as the electron‐deficient group have been synthesized for polymer solar cells. Compared toBDSeICwithout bromine substitution, these multibrominated materialsBDSeIC2BrandBDSeIC4Brexhibit lower energy levels, stronger absorption in the range of 500–900 nm, better crystalline quality, and enhanced electron mobility. The optimalBDSeIC2Br‐based devices withPM6as the donor, achieved a high power conversion efficiency (PCE) of up to 12.5% with a relatively low energy loss (Eloss) of 0.52 eV. The PCE of 12.5% for theBDSeIC2Br‐based devices are much higher than those devices based onPM6:BDSeIC(7.1%) orPM6:BDSeIC4Br(9.6%) blend films, and it is the highest reported PCE in binary PSCs with the brominated INCN end‐capped NF‐SMAs. Such outstanding PCE ofBDSeIC2Br‐based device is attributed to more balanced electron/hole mobility, higher charge dissociation and charge collection efficiency, and more proper phase separation features. These results indicate that introducing a benzo[1,2‐b:4,5‐b′]diselenophene core unit and bromine substiution on the end groups is an effective way to achieve high‐performance NIR absorption NF‐SMAs.