Enhanced Charge Transfer between Fullerene and Non-Fullerene Acceptors Enables Highly Efficient Ternary Organic Solar Cells
Enhanced Charge Transfer between Fullerene and Non-Fullerene Acceptors Enables Highly Efficient Ternary Organic Solar Cells
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富勒烯和非富勒烯受体之间增强的电荷转移可实现高效三元有机太阳能电池
DOI：
10.1021/acsami.8b16131
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发表时间：
2018
影响因子：
9.5
通讯作者：
Hongzheng Chen
中科院分区：
文献类型：
--
作者：
Lingling Zhan;Shuixing Li;Shuhua Zhang;Xingzhi Chen;Tsz-Ki Lau;Xinhui Lu;Minmin Shi;Chang-Zhi Li;Hongzheng Chen
驱动力不足，即前线分子轨道在施主和受主之间的能量偏移，影响了有机太阳能电池中的电荷分离，从而限制了量子效率的提高。在这里，我们论证了通过三元策略加强富勒烯和非富勒烯受体之间的电荷转移是解决这一问题的有效方法。通过将电子受体[6，6-苯基-C71-丁酸甲酯(6，6-苯基-C71-丁酸甲酯(PC71BM))作为第三组分引入到基于poly[(2，6-(4，8-bis(5-(2-ethylhexyl)-4-fluorothiophen-2-yl)-benzo[1，2-的聚合物给体的二元共混物中(b：4，5-b‘dithihene))-alt-(5，5-(1’，3‘-di-2-thienyl-5’，7‘-bis(2-ethylhexyl)benzo[1’，2‘-c：4’，2，2‘-((2 Z，2’-Z)-(((2，5-difluoro-1，4-phenylene)bis(4，4-bis(2-ethylhexyl)-4 H-环戊二烯[2，1-b：3，4-b‘dithiophene-6，2-diyl))bis(methanylylidene))bis(5，6-difluoro-3-oxo-2，3-dihydro-1 H-吲烯-2，1-二亚甲基)])的小分子受体(HF-PCIC)或2，2’-((2 Z，2‘-Z)-(((2，5-difluoro-1，4-phenylene)bis(4，4-bis(2-ethylhexyl)-4 H-环戊烷[2，1-b：3，4-b’dithiophene-6，2-diyl))bis(methanylylidene))bis(5，6-dichloro-3-oxo-2，3-dihydro-1 H-indene-2，1-diylidene])二丙二腈(HC-PCIC)具有未熔合的核，在较长波长范围内，其量子效率可从∼的70%提高到80%以上。PC71BM具有较低的能级和较高的电子迁移率，有利于三元OSCs中的电荷转移和输运，从而提高了量子效率。结果表明，基于PBDB-TF/HF-PCIC/PC71BM和PBDB-TF/HC-PCIC/PC71BM的三元OSC具有较高的功率转换效率，分别为11.55%和12.36%。此外，两种三元OSCs都表现出了良好的热稳定性，在130C热处理12h后，保持了∼80%的初始PCEs，表明含有富勒烯/非富勒烯受体的活性层形态稳定。这项工作揭示了通过调节能级来增强富勒烯和非富勒烯受体之间电荷转移的高效和热稳定的三元OSCs，这有助于更好地理解三元OSCs的工作机理。
Insufficient driving forces defined as the energetic offsets of the frontier molecular orbitals between a donor and an acceptor influence the charge separation in organic solar cells (OSCs), thus restricting the improvement of quantum efficiencies. Herein, we demonstrate that enhancing charge transfer between fullerene and non-fullerene acceptors via ternary strategy is an effective method to address this problem. By introducing an electron acceptor [6,6-phenyl-C71-butyric acid methyl ester (PC71BM) as the third component to the binary blends based on the polymer donor of poly[(2,6-(4,8-bis(5-(2-ethylhexyl)-4-fluorothiophen-2-yl)-benzo[1,2- b:4,5- b'dithiophene))- alt-(5,5-(1',3'-di-2-thienyl-5',7'-bis(2-ethylhexyl)benzo[1',2'- c:4',5'- c'dithiophene-4,8-dione) (PBDB-TF) and the small-molecule acceptor of 2,2'-((2 Z,2' Z)-(((2,5-difluoro-1,4-phenylene)bis(4,4-bis(2-ethylhexyl)-4 H-cyclopenta[2,1- b:3,4- b'dithiophene-6,2-diyl))bis(methanylylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1 H-indene-2,1-diylidene))dimalononitrile (HF-PCIC) or 2,2'-((2 Z,2' Z)-(((2,5-difluoro-1,4-phenylene)bis(4,4-bis(2-ethylhexyl)-4 H-cyclopenta[2,1- b:3,4- b'dithiophene-6,2-diyl))bis(methanylylidene))bis(5,6-dichloro-3-oxo-2,3-dihydro-1 H-indene-2,1-diylidene))dimalononitrile (HC-PCIC) with unfused cores, the quantum efficiencies can be boosted from ∼70% for binary blends to over 80% for ternary blends in the longer wavelength ranges. PC71BM shows lower energy levels and higher electron mobility, benefiting the charge transfer and transport in ternary OSCs and resulting in an enhanced quantum efficiency. As a result, ternary OSCs based on PBDB-TF/HF-PCIC/PC71BM and PBDB-TF/HC-PCIC/PC71BM exhibit high power conversion efficiencies (PCEs) of 11.55 and 12.36%, respectively. In addition, excellent thermal stabilities are realized for both ternary OSCs, which retained ∼80% initial PCEs after thermal treatment at 130 °C for 12 h, indicating that the active layer morphology containing fullerene/non-fullerene acceptors is stabilized. This work demonstrates efficient and thermally stable ternary OSCs with enhanced charge transfer between fullerene and non-fullerene acceptors via the modulation of energy levels, which helps to better understand the working mechanism of ternary OSCs.