摘要
为了提高有机太阳能电池(Organic solar cells, OSCs)给体材料的光吸收效率,本文设计了系列以噻吩异靛蓝分子片段为中心,不同芳香杂环为π-桥,1,8-萘酰二胺(1,8-Naphthalimide, NI)分子片段为端基的新型π-共轭化合物作为有机太阳能电池给体材料.利用量子化学中的密度泛函理论和含时密度泛函理论方法,对所设计的化合物的光学和电子性质进行了研究,探究分子结构与光谱和电子性质之间的联系.计算结果表明,通过在母体化合物中引入不同的π-桥,可以有效调节所设计分子的前线分子轨道能级、能隙和光谱性质.但是,其对设计分子的几何结构影响不大.设计的化合物分子均具有窄的能隙,在可见光和近红外光谱(NIR)区都有强吸收,这有利于提高有机太阳能电池光吸收效率.前线分子轨道能级分析发现,部分设计的化合物能级与典型富勒烯受体材料相匹配,可选用传统PCBM,bisPCBM和PC_(71)BM作为受体材料,另一部分设计化合物,则应考虑选用其他的太阳能电池受体材料.研究结果表明,本文所设计的化合物可作为具有红光或NIR区有强吸收的高效太阳能电池给体材料应用于太阳能电池中.本研究为开发和合成新型高效有机太阳能给体材料提供理论依据.
Due to traditional energy depletion and environmental pollution, organic solar cells(OSCs) have attracted considerable attentions because their outstanding advantages such as low cost, easy fabrication, light weight, and compa-tibility with flexible substrates. The power conversion efficiency(PCE) of OSCs has rapidly increased over 10% recently owing to the tremendous efforts on improving their performance. Among the various OSCs such as dye-sensitized solar cells(DSSCs), polymer solar cells(PSCs), and small molecules based OSCs(SMOSCs), SMOSCs have attracted much more attention due to their unique advantage of well defined molecular structure, high purity, easy functionalization, and excellent batch-to-batch reproducibility. Unfortunately, compared to PSCs, the overall performance of SMOSCs still lags behind that of their PSCs counterparts due to the drawbacks of poor inferior film quality and interconnectivity and low thermal stability in solid films for small molecules. Therefore, in order to improve the performance of SMOSCs, it is necessary to look for appropriate small molecules. They should exhibit suitable frontier molecular orbitals(FMOs) energy levels, good film forming ability, high charge carrier mobility, lower band gap, and miscibility with fullerene derivatives as an acceptor. The small molecules donors should possess deep highest occupied molecular orbital energy level and narrow band gap. Moreover, in order to ensure the effective exciton splitting and charge dissociation, the downhill energetic driving force(ΔEL-L) should at least amount to 0.2 eV. Among the various small molecular donors for SMOSCs, the thienoisoindigo and 1,8-naphthalimide(NI) derivatives are promising candidate building blocks in terms of their larger π-conjugated system, higher mobility, broadened absorption region, and good coplanarity. In order to obtain high light-absorption efficiency of OSCs, a series of novel π-conjugated molecules with thienoisoindigo fragments as cores, NI fragments as end-caps, and different conjugate π-bridges have been designed for OSCs applications. Using density functional theory(DFT) and time-dependent DFT(TD-DFT) methods, their electronic and optical properties were studied systematically. The calculation results showed that the different π-bridges can effectively tune the FMO energy level, energy gap, and absorption spectra. The calculated FMOs energies and spectral properties showed that the designed molecules possess narrower band gaps and strong absorption in the red/near-infrared(NIR) region, which led to the higher light-absorbing efficiency. Additionally, the FMOs analysis has turned out that some designed molecules provide the best match matched energy levels with typical acceptors [6,6]-Phenyl-C61-butyric acid methyl ester(PCBM), and its derivatives bisPCBM and PC_(71)BM, while others designed molecules should select other acceptors of OSCs. The results reveal that the designed molecules can serve as high-efficiency red/NIR-active donor materials in OSC applications.
作者
崔克宇
孙涛
石静敏
王良
CUI Ke-yu;SUN Tao;SHI Jing-min;WANG Liang(College of Chemistry,Jilin Normal University,Siping 136000,China;College of Environmental Science and Engineering,Jilin Normal University,Siping 136000,China)
出处
《分子科学学报》
CAS
北大核心
2023年第1期87-94,共8页
Journal of Molecular Science
基金
吉林省人力资源与社会保障厅项目(2021Z007)。
