合成以苯并三噻吩(Benzotrithiophene)為電子予體之予-受體共軛高分子應用於異質接面太陽能電池之探討

Abstract

在本研究中，我們合成一系列含有以苯并三噻吩為電子予體之予-受體共軛高分子，並應用於應用於異質接面太陽能電池製程最佳化之研究。 并三噻吩(Benzotrithiophene, BTT)為一具有推電子能力且平面性佳的結構，同時具有多電子、高的電荷載子遷移率，因此苯并三噻吩很適合作為予-受共軛高分子中的予體。 PBTT4BT與 PBTT4BO皆以Benzotrithiophene (BTT)為電子予體，分別以Benzothiadiazole (BT)和Benzoxadiazole (BO) 為電子受體，並在予體(BTT)和受體(BT)之間加入Spacer(4-dodecylthiophene)，希望藉由其來增加共聚高分子的共軛性以及增加溶解度。根據XRD分析兩者皆有結晶性，又PBTT4BT/PC71BM元件性質最佳化是在熱退火溫度150 °C下20 min ，其中 Voc 為0.72V，Jsc 為11.58mAcm-2 ，FF為67%， 得到最佳效率為 5.6%。 PBTT4BO-OD與PBTT4BO-UD皆以BTT為電子予體， BO為電子受體，差別在於BTT中的烷基側鏈長度不同，PBTT4BO-OD/ PC71BM最佳化條件是在加入0.1%DIO後再繼續進行熱退火溫度於120 °C 下 1 min，其中Voc為 0.75V，Jsc為11.29mAcm-2，FF為64%，得到最佳效率為5.4%。

In this study, we synthesize a series of main chain donor-acceptor conjugated copolymers using benzotrithiophene(BTT) as donor for application in polymer bulk heterojunction(BHJ) polymer solar cells. The BTT unit , featured a rigid and planar structure , has the ability to push electronics and improve charge carrier mobility of polymers. BTT4BT and PBTT4BO composed of benzotrithiophene ( BTT) units as donor, benzothiadiazole(BT) and benzoxadiazole (BO) units as accepters, respectively, as acceptors , and 4-dodecylthiophene as conjugation spacer. Both PBTT4BO and PBTT4BT formed edge-on lamellae as evidenced from their XRD patterns. After thermal annealing, the efficiency of the PBTT4BT/PC71BM device improved further to 5.6%, with a value of VOC of 0.72 V, a value of JSC of 11.58 mAcm–2 and a fill factor of 67%. Subsequently , we have used Stille coupling polymerization to prepare a serious of new crystalline , conjugated polymers- PBTT4BO-OD and PBTT4BO-UD—featuring difference alkyl side chain length of BTT unit. A device incorporating PBTT4BO-OD and PC71BM (blend weight ratio, 1:1), with DIO (0.1vol%) as an additive, and then thermal annealing(120 °C ,1 min), device improved further to 5.4%, with a value of VOC of 0.75 V, a value of JSC of 11.29 mAcm–2 and a fill factor of 64%.