School of Chemistry and Chemical Engineering, Southeast University, Nanjing, Jiangsu Province, 211189, China.
Department of Materials Science and Engineering and The Shenzhen Key Laboratory for Printed Organic Electronics, Southern University of Science and Technology (SUSTech), No. 1088, Xueyuan Road, Shenzhen, Guangdong, 518055, China.
Macromol Rapid Commun. 2020 Jun;41(12):e2000144. doi: 10.1002/marc.202000144. Epub 2020 May 13.
A new polymer acceptor poly{(N,N'-bis(2-ethylhexyl)-1,4,5,8-naphthalenedicarboximide-2,6-diyl)-alt-5,5-(3,3'-didodecyl-2,2'-bifuran)} (NDI-BFR) made from naphthalenediimide (NDI) and furan-derived head-to-head-linked 3,3'-dialkyl-2,2'-bifuran (BFR) units is reported in this study. Compared to the benchmark polymer poly(naphthalenediimide-alt-bithiophene) (N2200), NDI-BFR exhibits a larger bathochromic shift of absorption maxima (842 nm) with a much higher absorption coefficient (7.2 × 10 m cm ), leading to an ultranarrow optical bandgap of 1.26 eV. Such properties ensure good harvesting of solar light from visible to the near-infrared region in solar cells. Density functional theory calculation reveals that the polymer acceptor NDI-BFR possesses a higher degree of backbone planarity versus the polymer N2200. The polymer NDI-BFR exhibits a decent electron mobility of 0.45 cm V s in organic thin-film transistors (OTFTs), and NDI-BFR-based all-polymer solar cells (all-PSCs) achieve a power conversion efficiency (PCE) of 4.39% with a very small energy loss of 0.45 eV by using the environmentally friendly solvent 1,2,4-trimethylbenzene. These results demonstrate that incorporating head-to-head-linked BFR units in the polymer backbone can lead to increased planarity of the polymer backbone, reduced optical bandgap, and improved light absorbing. The study offers useful guidelines for constructing n-type polymers with narrow optical bandgaps.
本研究报道了一种新型聚合物受体聚{（N，N'-双（2-乙基己基）-1,4,5,8-萘二酰亚胺-2,6-二基）-交替-5,5-（3,3'-二十二烷基-2,2'-联呋喃）}（NDI-BFR），它由萘二酰亚胺（NDI）和呋喃衍生的头对头连接的 3,3'-二烷基-2,2'-联呋喃（BFR）单元制成。与基准聚合物聚（萘二酰亚胺-联噻吩）（N2200）相比，NDI-BFR 表现出更大的吸收最大值的红移（842nm）和更高的吸收系数（7.2×10^4m^1cm^-1），导致超窄光学带隙为 1.26eV。这些特性确保了太阳能电池能够从可见光到近红外区域有效地收集太阳光。密度泛函理论计算表明，与聚合物 N2200 相比，聚合物受体 NDI-BFR 具有更高的主链平面度。聚合物 NDI-BFR 在有机薄膜晶体管（OTFTs）中表现出相当高的电子迁移率 0.45cm^2V^-1s^-1，基于 NDI-BFR 的全聚合物太阳能电池（all-PSCs）在使用环保溶剂 1,2,4-三甲苯时，可获得 4.39%的功率转换效率（PCE），能量损耗非常小，为 0.45eV。这些结果表明，在聚合物主链中引入头对头连接的 BFR 单元可以提高聚合物主链的平面度、降低光学带隙并提高光吸收。该研究为构建具有窄光学带隙的 n 型聚合物提供了有用的指导。
