Hydrophilic poly(triphenylamines) with phosphonate groups on the side chains: synthesis and photovoltaic applications
作者:Xiaofeng Xu、Yongxiang Zhu、Lianjie Zhang、Jiangman Sun、Jun Huang、Junwu Chen、Yong Cao
DOI:10.1039/c1jm14970a
日期:——
Two triphenylamine-based homopolymers PTPA-EP and PTPA-PO3Na2, comprising diethyl phosphonate and sodium phosphonate end groups on side chains, respectively, were synthesized. The UV-vis absorption and photoluminescence (PL) properties of the PTPA-EP and PTPA-PO3Na2 are mainly determined by the conjugated poly(triphenylamine) main chain. The PTPA-EP and PTPA-PO3Na2 possess comparable HOMO levels of around −5.03 eV. The PTPA-EP, with better solubility than PTPA-PO3Na2 in hydrophilic solvents, was utilized as cathode interlayer to construct efficient bulk-heterojunction photovoltaic cells with a low bandgap poly(2,7-carbazole) (PCDTBT) as the polymer donor and [6,6]-phenyl C71-butyric acid methyl ester (PC71BM) as the acceptor. The work function of ITO was shifted to −4.3 eV by PTPA-EP, which matches well with the LUMO level of PC71BM for good electron extraction. Inverted solar cells with a device configuration of ITO/PTPA-EP/active layer/MoO3/Al exhibited a power conversion efficiency (PCE) of 4.59%, which is a good efficiency among inverted solar cells with an organic interlayer on an ITO cathode. The PCE shows a 79% increase in comparison to that of a bare ITO cathode, though the efficiency is lower than 5.13% for an inverted solar cell with an inorganic ZnO interlayer on ITO. Moreover, a conventional solar cell with a device configuration of ITO/PEDOT:PSS/active layer/PTPA-EP/Al could show a better PCE of 5.27%. The results indicate that PTPA-EP is a promising new cathode interlayer for high efficiency inverted and conventional solar cells.
合成了两种三苯胺基均聚物 PTPA-EP 和 PTPA-PO3Na2,它们的侧链上分别含有膦酸二乙酯和膦酸钠端基。PTPA-EP 和 PTPA-PO3Na2 的紫外可见吸收和光致发光(PL)特性主要由共轭聚(三苯胺)主链决定。PTPA-EP 和 PTPA-PO3Na2 的 HOMO 水平相当,约为 -5.03 eV。与 PTPA-PO3Na2 相比,PTPA-EP 在亲水性溶剂中的溶解性更好,因此,利用 PTPA-EP 作为阴极中间膜,以低带隙聚 2,7-咔唑(PCDTBT)作为聚合物供体,以 [6,6]-Phenyl C71-butyric acid methyl ester(PC71BM)作为受体,构建了高效的体外异质结光伏电池。PTPA-EP 将 ITO 的功函数移至 -4.3 eV,这与 PC71BM 的 LUMO 电平非常吻合,从而实现了良好的电子萃取。器件配置为 ITO/PTPA-EP/活性层/MoO3/Al 的反相太阳能电池的功率转换效率(PCE)为 4.59%,这是在 ITO 阴极上使用有机中间膜的反相太阳能电池中效率较高的一种。与裸 ITO 阴极相比,PCE 提高了 79%,尽管效率低于在 ITO 上使用无机 ZnO 中间膜的反相太阳能电池的 5.13%。此外,ITO/PEDOT:PSS/活性层/PTPA-EP/Al 器件配置的传统太阳能电池的 PCE 更高,可达 5.27%。研究结果表明,PTPA-EP 是一种很有前途的新型阴极中间膜,可用于高效反相和传统太阳能电池。