Highly efficient polymer solar cells based on poly(carbazole-alt-thiophene-benzofurazan)
作者:Bin Zhang、Xiaowen Hu、Minquan Wang、Huiping Xiao、Xiong Gong、Wei Yang、Yong Cao
DOI:10.1039/c2nj40309a
日期:——
An octyloxy substituted benzofurazan based poly(carbazole-alt-thiophene-benzofurazan) (PCzDTBF) was synthesized by Suzuki polycondensation. The absorption spectra of the polymer were peaked at 385 and 540 nm, and the HOMO and LUMO energy levels were −5.34 and −3.46 eV, respectively. The hole mobility was found to be 4.8 × 10−4 cm2 V−1 S−1 by the space charge limited current (SCLC) method, and the surface energy (Es) was calculated to be 35.8 mJ m−2 from the contact-angle measurement. Polymer solar cells (PSCs) based on the blend of PCzDTBF and PCBM with a weight ratio of 1 : 2 were fabricated. The devices were found to have a power conversion efficiency (PCE) of 4.2% in the device configuration of ITO/PSS:PEDOT/PCzDTBF:PC70BM/Al. By utilizing poly[(9,9-dioctyl-2,7-fluorene)-alt-(9,9-bis(3′-(N,N-dimethylamino)propyl)-2,7-fluorene)] (PFN) as the cathode interfacial layer, the PCE was enhanced to 5.48%, with an open-circuit voltage (Voc) of 0.90 V, a short-circuit current density (Jsc) of 7.73 mA cm−2, and a fill factor (FF) of 67%. The high efficiencies could be ascribed to the good morphology, resulting from the matched surface energies of the PCzDTBF and PCBM components, and the distinct enhancement on Voc and FF by the PFN layer, where it is possible that a built-in field potential exists between the active layer and cathode.
通过铃木聚合偶联反应合成了一种基于辛氧基取代苯并呋咱的聚(咔唑-alt-噻吩-苯并呋咱)(PCzDTBF)。该聚合物的吸收光谱在385和540 nm处有峰,最高占据分子轨道(HOMO)和最低未占据分子轨道(LUMO)能级分别为−5.34和−3.46 eV。通过空间电荷限制电流(SCLC)法测得空穴迁移率为4.8 × 10−4 cm² V⁻¹ S⁻¹,通过接触角测量计算得出表面能(Es)为35.8 mJ m⁻²。基于PCzDTBF和PCBM以1:2的质量比例混合制备了聚合物太阳能电池(PSCs)。在ITO/PSS:PEDOT/PCzDTBF:PC70BM/Al的器件结构中,器件的功率转换效率(PCE)为4.2%。利用聚[(9,9-二辛基-2,7-芴)-alt-(9,9-双(3′-(N,N-二甲基氨基)丙基)-2,7-芴)](PFN)作为阴极界面层,PCE提升至5.48%,开路电压(Voc)为0.90 V,短路电流密度(Jsc)为7.73 mA cm⁻²,填充因子(FF)为67%。高效率可归因于PCzDTBF和PCBM组分之间匹配的表面能导致的良好形态,以及PFN层对Voc和FF的显著增强作用,可能是在活性层和阴极之间存在内置场电位。