以環烯單元為共軛架橋之非金屬系光敏染料暨太陽能電池

Abstract

本論文利用Stille coupling、Buchwald-Hartwig coupling、McMurry reaction與Knoevenagel condensation等反應，合成出一系列新穎非金屬系有機光敏染料（metal-free organic dyes）。此系列染料以arylamine作為電子予體（donor），2-cyanoacrylic acid為電子受體（acceptor），兩者之間的共軛架橋（spacer）則由環烯單元（locked olefin）搭配呋喃（furan）、噻吩（thiophene）等芳香雜環所組成。 此系列染料有明顯的電荷轉移吸收，其吸收波長（λabs）約在428−455 nm之間，莫耳消光係數也可達24000−41500 M-1 cm-1。由電化學量測推算出此系列染料之HOMO與LUMO能階範圍分別約在5.43−5.69與3.35−3.52 eV之間，因此染料皆可以順利還原再生及其電子皆有利於注入TiO2光導電極。其組裝成的染料敏化太陽能電池（dye-sensitized solar cells, DSSCs）呈現不錯的光電轉換效率，其範圍為3.10−5.86%。在相同條件下和N719染料製成的標準元件比較，可達N719染料元件效率的43−82%。A novel series of metal-free organic dyes were synthesized via Stille coupling, Buchwald-Hartwig coupling, McMurry reaction and Knoevenagel condensation. These dyes are composed of a diarylamine moiety as the electron donor, a conjugated spacer containing locked olefin, furan and thiophene as the electron transmitting bridge, and 2-cyanoacrylic acid as the electron acceptor and anchoring group to the TiO2 surface. These dyes possess a π−π* transition band ranging from 428 to 455 nm in the electronic absorption spectra. The band has prominent charge transfer character and the molar extinction coefficient ranges from 24000 to 41500 M-1cm-1. From cyclic voltammetry measurement, the HOMO and LUMO energy levels of these dyes calculated from the cyclic voltammograms were in the range of 5.43−5.69 and 3.35−3.52 eV, respectively, which facilitated both electron injection and dye regeneration. Nanocrystalline TiO2 dye-sensitized solar cells (DSSCs) using these dyes exhibit high solar energy-to-electricity conversion efficiencies ranging between 3.10−5.86%, which reach 43−82% of a standard device of N719 fabricated and measured under same conditions.