Rajalingam Agneeswari, Danbi Kim*, Vellaiappillai Tamilavan*, Chnan-gi Shin, Sung Heum Park*, and Youngeup Jin†
Department of Industrial Chemistry, Pukyong National University, Busan 48513, Korea
*Department of Physics, Pukyong National University, Busan 48513, Korea
Rajalingam Agneeswari · 김단비* · Vellaiappillai Tamilavan* · 신찬기 · 박성흠* · 진영읍†
부경대학교 공업화학과, *부경대학교 물리학과
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A new alternating copolymer, poly(3,6-bis(thiophen-2-yl)-2,5-bis(2-octyldodecyl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione-alt-3,5-di(thiophen-2-yl)-1,2,4-oxadiazole (PDPP4TO), was prepared and their properties were compared with the reported polymer, poly(2,5-bis(2-hexyldecyl)-3,6-di(thiophen-2-yl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione-alt-3-hexyl-2-(5-(3-hexylthiophen-2-yl)thiophen-2-yl)thiophene (PDPP5T), with the aim understanding the effects of inserting oxadiazole units on diketopyrrolopyrrole (DPP)-based polymer backbone. Surprisingly, the properties of DPP-based polymers were found to drastically change after inserting oxadiazoles on their backbone. Noticeably, PDPP4TO exhibited higher bandgap (⁓0.3 eV), and consequently showed good complementary absorption with non-fullerene acceptors, and deeper highest occupied molecular orbital (HOMO, ⁓0.16 eV) compared to those of PDPP5T. However, the photovoltaic devices made using PDPP4TO offered a lower power conversion efficiency (PCE, ⁓0.94%) compared to that of PDPP5T (⁓4.6%). Whereas, the PDPP4TO-based photovoltaic devices provided a significantly higher open-circuit voltage (Voc) than that of the PDPP5T-based devices. These results indicate that the insertion of oxadiazoles on DPP-based polymer backbones results in an enormous difference in their properties.
본 연구는 diketopyrrolopyrrole(DPP) 기반 고분자 골격에 옥사디아졸 단위를 삽입함으로써 고분자 특성에 미치는 효과를 알아보기 위해 신규 고분자 poly(3,6-bis(thiophen-2-yl)-2,5-bis(2-octyldodecyl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione-alt-3,5-di(thiophen-2-yl)-1,2,4-oxadiazole(PDPP4TO)을 개발하고 이전에 보고한 고분자 poly(2,5-bis(2-hexyldecyl)-3,6-di(thiophen-2-yl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione-alt-3-hexyl-2-(5-(3-hexylthiophen-2-yl)thiophen-2-yl)thiophene(PDPP5T)와 비교 분석하였다. DPP계 고분자는 백본에 oxadiazoles을 삽입한 후 특성이 급격히 변화됨을 확인하였다. 고분자 PDPP4TO는 PDPP5T에 비해 더 높은 밴드갭(~0.3 eV)을 가졌으며, 결과적으로 넌플러렌 수용체와 상보적으로 좋은 흡수대와 깊은 highest occupied molecular orbital(~0.16 eV)을 보였다. 그러나 PDPP4TO를 전자주개로 제작한 태양전지는 PDPP5T로 제작한 태양전지(PCE~4.6%)에 비해 상대적으로 낮은 전력 변환 효율(PCE~0.94%)을 보였다. 그러나 PDPP4TO로 제작된 태양전지는 PDPP5T 기반 태양전지보다 훨씬 높은 개방 회로 전압(Voc)을 제공했다. 이러한 결과는 DPP 기반 고분자 백본에 oxadiazoles을 삽입하면 그 성질에 큰 차이가 발생한다는 것을 나타낸다.
Keywords: organic solar cells, diketopyrrolopyrrole-based polymers, oxadiazole-based polymers.
2023; 47(1): 79-86
Published online Jan 25, 2023
Department of Industrial Chemistry, Pukyong National University, Busan 48513, Korea