含苯並噻二唑及卡唑共聚高分子之合成及其應用在有機太陽能電池之研究

Abstract

在本研究中，我們合成了三種單體有卡唑(Carbazole)、噻吩(Thiophene)以及苯並噻二唑(Benzothiadiazole)分別為主體且在苯乙烯4-號即對位上做連接，並以free radical聚合法，成功合成一系列的單聚物(Homopolymer)與共聚物(Copolymer)。共聚物部分為本研究主軸，施體端(Donor)為具有良好電洞傳導性的卡唑，且在卡唑9-號氮上連接具有六個碳的正己烷來提升共聚物高分子之溶解度，第二個單體結構為兩個噻吩一起連接，並調整增加共軛長度使其能階符合前段可見光吸收範圍內，另一方面預期作為三個單體之共聚物的電子電洞雙向傳導架橋，第三個單體為強電子受體(Acceptor)苯並噻二唑，第三個單體我們額外在苯並噻二唑結構兩端連接了兩個噻吩，使其能階可吸收後段可見光範圍；我們預期透過調控三種單體比例可以改善共聚物可見光吸收範圍、能階以及溶解度。此外我們對成功合成出的一系列的高分子P1~P6利用凝膠滲透層析儀、熱重分析儀、微差掃描卡計、紫外光/可見光分光光譜儀、螢光光譜儀以及循環伏安儀來做光電性質分析與探討，進而應用於有機太陽能電池元件的製作與討論。

In this study, we synthesized three type monomers : carbazole-containing、thiophene-containing、benzothiadiazole-containing. Carbazole was a great hole transporting material in OLED and OPV field. We expected that increasing of polymer solubility which was modified by n-Hexane on carbazole nitrogen site. We also used the Styrene (Para site) to connected with monomer via suzuki coupling reactions. All kind of polymers were synthesized via free radical polymerization. The homopolymers P1~P3 and the copolymers P4~P6 were successfully synthesized. All derivatives discovered good thermal stability, and 5% thermal degradation temperature over 350 oC. The optical properties showed that the absorption were red-shifted with the film state on absorption spectrum, It was indicated that copolymers P4~P6 had great interaction of π-πstacking molecular structure. The optical band gap of P4, P5 and P6 were 2.18 eV, 2.15 eV, 2.12 eV respectively. We also observed that the HOMO of these derivatives increased with increasing raio of carbazole unit. The preliminary bulk heterojunction solar cell devices were fabricated with poymer P1~P6. The highest power conversion efficiency were 0.22 %, containing weigh ratio with P6 : PCBM = 1:4 , VOC of 0.45 (V), ISC of 1.49 mA/cm2, and FF of 0.32 under AM 1.5G solar simulator.