| Summary: | 碩士 === 國立臺灣大學 === 高分子科學與工程學研究所 === 101 === Two different acceptor-donor-acceptor (A-D-A) five-membered heterocycles incorporated with rhodanine units as the terminal acceptor groups, TF-BT-FT and TT- BT-FF were synthesized for solution –processable organic small molecule solar cell. Furan was introduced onto the structure of TF-BT-FT to reduce the degree of distortion, along with octyl groups to acquire better molecular ordering. Moreover, TF-BT-FT and TT-BT-TT were end-capped with electron–deficient rhodanine units to broaden absorption regions. These small molecules exhibited good solubility and thermal stability. Investigated by UV-visible spectrophotometer, the absorption spectrum of TF-BT-FT is was red-shifted relative to that of TT-BT-TT. The bathochromic shift indicates that the TF-BT-FT exhibited a lower band gap than did TT-BT-TT. The influence of the planarity on the effective conjugation length of the molecule can lead to the tuning of HOMO energy level. Inverted OSCs with ZnOx and MoO3 as an electron extraction layer and a hole extraction layer, respectively were fabricated by spin-coating the blend of TT-BT-TT or TF-BT-FT as donor and the fullerene derivative (PC61BM) as acceptor. The TF-BT-FT and TT-BT-TT based BHJ solar cell inverted devices achieved a PCE of 0.49 % with a Voc of 0.71 V, a Jsc of 2.31 mAcm-2 and an FF of 0.29, and PCE of 0.43 % with a Voc of 0.73 V, a Jsc of 1.94 mAcm-2 and an FF of 0.30, respectively. The preliminary photovoltaic performances indicate that the photocurrent and power conversion efficiency were benefited greatly by inserting furan as five-membered heterocycles in small molecules.
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