Kim, Ji-Hoon Song, Chang Eun Kim, BongSoo Kang, In-Nam Shin, Won Suk Hwang, Do-Hoon 2024-01-20T10:33:23Z 2024-01-20T10:33:23Z 2021-09-05 2014-01-28 0897-4756 https://pubs.kist.re.kr/handle/201004/127206 We designed and synthetized a new poly{4,8-bis((2-ethylhexyl)thieno[3,2-b]thiophene)-benzo[1,2-b:4,5-b']dithiophene-alt-2-ethylhexyl-4,6-di- bromo-3-fluorothieno[3,4-b]thiophene-2-carboxylate} (PTTBDT-FTT) comprising bis(2-ethylhexylthieno[3,2-b]thiophenylbenzo[1,2-b:4,5-b']dithiophene (TTBDT) and 2-ethylhexyl 3-fluorothieno[3,4-b]thiophene-2-carboxylate (FTT). The optical bandgap of PTTBDT-FTT was 1.55 eV. The energy levels of the highest occupied and lowest unoccupied molecular orbitals of PTTBDT-FTT were -5.31 and -3.73 eV, respectively. Two-dimensional grazing-incidence X-ray scattering measurements showed that the film's PTTBDT-FTT chains are predominantly arranged with a face-on orientation with respect to the substrate, with strong pi-pi stacking. An organic thin-film transistor fabricated using PTTBDT-FTT as the active semiconductor showed high hole mobility of 2.1 x 10(-2) cm(2)/(V.s). Single-junction bulk heterojunction photovoltaic cells with the configuration ITO/PEDOT:PSS/PTTBDT-FTT:PC71BM/Ca/Al were fabricated, which showed a maximum power conversion efficiency (PCE) of 7.44%. Inverted photovoltaic cells with the structure ITO/PEIE/PTTBDT-FTT:PC71/BM/MoO3/Ag were also fabricated, with a maximum PCE of 7.71%. A tandem photovoltaic device comprising the inverted PTTBDT-FTT:PC71BM cell and a P3HT:ICBA-based cell as the top and bottom cell components, respectively, showed a maximum PCE of 8.66%. This work demonstrated that the newly developed PTTBDT-FTT polymer was very promising for applications in both single and tandem solar cells. Furthermore, this work highlighted the fact that an extended pi-system in the electron-donor moiety in low bandgap polymers is crucial for improving polymer solar cells. English AMER CHEMICAL SOC OPEN-CIRCUIT VOLTAGE POWER CONVERSION EFFICIENCY HETEROJUNCTION SOLAR-CELLS CONJUGATED POLYMER BENZODITHIOPHENE ELECTRONICS COPOLYMERS Thieno[3,2-b]thiophene-Substituted Benzo[1,2-b:4,5-b ']dithiophene as a Promising Building Block for Low Bandgap Semiconducting Polymers for High-Performance Single and Tandem Organic Photovoltaic Cells Article 10.1021/cm4035903 1 CHEMISTRY OF MATERIALS, v.26, no.2, pp.1234 - 1242 CHEMISTRY OF MATERIALS 26 2 1234 1242 scie scopus 000330543600044 2-s2.0-84893447638 Chemistry, Physical Materials Science, Multidisciplinary Chemistry Materials Science Article OPEN-CIRCUIT VOLTAGE POWER CONVERSION EFFICIENCY HETEROJUNCTION SOLAR-CELLS CONJUGATED POLYMER BENZODITHIOPHENE ELECTRONICS COPOLYMERS Organic photovoltaic cells Low bandgap polymer Tandem polymer solar cells