Study on exploitation of near-infrared dyes for organic photovoltaic cells

吸收近红外光的高共轭有机化合物是提高有机光伏电池性能的重要材料。在这项研究中，我们合成了一种新的骨架轴承近红外吸收染料，并研究其电子性质以及潜在的有机光致变色电池材料的解决方案处理制造其前体。当二维π体系如卟啉与苯单元稠合时，必然存在两个主要的跃迁：沿着稠合环定向的纵向跃迁和由于单个卟啉环引起的短跃迁。因此，即使具有最长波长的吸收达到近红外区域，强吸收仍保持在可见光区域。另一方面，硼-二吡咯亚甲基（BODIPY）的π体系是一维扩散的，在约100 nm处有一个强吸收带。500纳米。我们成功地合成了仅在近红外区域具有吸收的bisBODIPY染料，这是由于通过BODIPY发色团以纵向方式融合的纵向跃迁。此外，我们还成功地在空气中引入吸电子基团，制备了稳定的近红外染料。目前，合作公司正在进行近红外专用滤光片、有机光伏电池等的应用研究。

Highly conjugated organic compounds absorbing near-infrared light are essential materials for improvement of organic photovoltaic cells. In this study, we synthesize dyes with a novel skeleton bearing near-infrared absorption and investigate their electronic properties as well as potentials for organic photovoltaic-cell materials by the solution-processed fabrication of their precursors. When the two-dimensional πsystems such as porphyrins are fused with a benzene unit, there must be two major transitions: a longitudinal transition directed along the fused rings and short transitions due to the individual porphyrin rings. Therefore, strong absorption remains in a visible region, even if the absorption with the longest wavelength reaches to the near-infrared region. On the other hand, the πsystem of boron-dipyrromethene (BODIPY) spreads one-dimensionally and has one strong absorption band at ca. 500 nm. We succeeded in the synthesis of bisBODIPY dyes having absorption only in the near-infrared region due to the longitudinal transition by fusion of the BODIPY chromophores in the longitudinal fashion. In addition, we succeeded inthe preparation of stable near-infrared dyes under air by introduction of electron-withdrawing groups. Now, the application studies for near-infrared specific filters, organic photovoltaic cells, etc. are underway in the cooperative companies.