scholarly journals The Effects of Molecular Packing Behavior of Small-Molecule Acceptors in Ternary Organic Solar Cells

2021 ◽  
Vol 11 (2) ◽  
pp. 755
Author(s):  
Eunhee Lim

Herein, two diketopyrrolopyrrole (DPP)-based, small-molecule isomers, o- and p-DPP-PhCN, were introduced as acceptors in ternary organic solar cells (OSCs). The isomers have the same molecular backbone but differ in the positions of the cyanide (CN) substituents (ortho and para), which greatly affects their packing behavior. Ternary solar cells composed of poly(3-hexylthiophene) (P3HT):DPP-PhCN:phenyl-C61-butyric acid methyl ester (PCBM) were fabricated, and the effects of the different packing behaviors of the third component on the device performance and the working mechanism of the ternary cells were investigated. The addition of o-DPP-PhCN with a relatively high-lying lowest unoccupied molecular orbital energy level resulted in an increase in the open-circuit voltage (VOC) in the ternary devices, demonstrating the alloy-like structure of the two acceptors (o-DPP-PhCN and PCBM) in the ternary system. However, the p-DPP-PhCN-based ternary cells exhibited VOC values similar to that of a P3HT:PCBM binary cell, irrespective of the addition of p-DPP-PhCN, indicating a cascade energy-level structure in the ternary system and an effective charge transfer from the P3HT to the PCBM. Importantly, by increasing the addition of p-DPP-PhCN, the short-circuit current density increased substantially, resulting in pronounced shoulder peaks in the external quantum efficiency responses in the long-wavelength region, corresponding to the contribution of the photocurrent generated by the light absorption of p-DPP-PhCN. Despite sharing the same molecular backbone, the two DPP-PhCNs exhibited substantially different packing behaviors according to the position of their CN substituents, which also greatly affected the working mechanism of the ternary devices fabricated using the DPP-PhCNs as the third component.

2015 ◽  
Vol 93 (11) ◽  
pp. 1181-1190 ◽  
Author(s):  
Dongmei Wang ◽  
Zhiyuan Geng

To seek high-performance oligomer donor materials used in organic solar cells, four star-shaped molecules with a planar donor core derived from the recent reported molecule 3T-P-DPP (phenyl-1,3,5-trithienyl-diketopyrrolopyrrole) were designed. The molecular properties affecting the cell performance, such as structural characteristics, frontier molecular orbital energy level, absorption spectra, exciton character, and charge transfer/transport, were investigated by means of the density functional theory and time-dependent density functional theory methods. Comparative analysis showed that the new designed molecule 3 with a TTT (2,4,6-tri(thiophen-2-yl)-1,3,5-triazine) core has better planarity, a lower HOMO energy level, and a higher absorption efficiency, as well as more favorable exciton dissociation and charge transfer than the others, potentially improving the open-circuit voltage and short-circuit current density. Consequently, 3 maybe superior to 3T-P-DPP and may act as a promising donor material candidate for organic solar cells.


2018 ◽  
Vol 3 (1) ◽  
pp. 131-141 ◽  
Author(s):  
Yan Zou ◽  
Yue Wu ◽  
Hang Yang ◽  
Yingying Dong ◽  
Chaohua Cui ◽  
...  

The engineering of alkylthio side chains in the molecular conjugated backbone of small molecules is in favor of achieving a linear molecular backbone conformation, slightly red-shifting the absorption spectrum, and down-shifting the HOMO energy level of the resulting molecule.


Author(s):  
Rashmirekha Pradhan ◽  
Hemraj Dahiya ◽  
Bhawani Prasad Bag ◽  
Mukhamed L. Keshtov ◽  
Rahul Singhal ◽  
...  

Despite their minimal HOMO energy level offset promising power conversion efficiencies up to 13.54% have been recorded for ternary organic solar cells using coumarin-based molecular donors and fullerene-free acceptors.


2016 ◽  
Vol 4 (14) ◽  
pp. 5288-5293 ◽  
Author(s):  
Liangang Xiao ◽  
Ke Gao ◽  
Yangdong Zhang ◽  
Xuebin Chen ◽  
Lintao Hou ◽  
...  

We successfully developed a ternary system by introducing a low band gap material of DPPEZnP-O into a PTB7 : PC71BM blend to improve the photovoltaic properties of BHJ solar cells.


2021 ◽  
Author(s):  
Seunggyun Hong ◽  
Chang Eun Song ◽  
Du Hyeon Ryu ◽  
Sang Kyu Lee ◽  
Won Suk Shin ◽  
...  

In this paper, two cyclohexyl-substituted non-fullerene small molecules, T2-Cy6MRH and T2-Cy6PRH, are designed to have the same molecular backbone of a bithiophene (T2) core and rhodanine (RH) end groups. T2-Cy6MRH...


2018 ◽  
Vol 20 (38) ◽  
pp. 24570-24576 ◽  
Author(s):  
Zhen Wang ◽  
Guangchao Han ◽  
Lingyun Zhu ◽  
Yuan Guo ◽  
Yuanping Yi ◽  
...  

Introducing a proper amount of the third component in ternary blend organic solar cells can result in a significant decrease of docking PC71BM with the central electron-donating unit of electron donors and thus suppress charge recombination.


2019 ◽  
Vol 16 (3) ◽  
pp. 236-243 ◽  
Author(s):  
Hui Zhang ◽  
Yibing Ma ◽  
Youyi Sun ◽  
Jialei Liu ◽  
Yaqing Liu ◽  
...  

In this review, small-molecule donors for application in organic solar cells reported in the last three years are highlighted. Especially, the effect of donor molecular structure on power conversion efficiency of organic solar cells is reported in detail. Furthermore, the mechanism is proposed and discussed for explaining the relationship between structure and power conversion efficiency. These results and discussions draw some rules for rational donor molecular design, which is very important for further improving the power conversion efficiency of organic solar cells based on the small-molecule donor.


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