In recent years, organic photoactive materials with nonconjugated rings have attracted a lot of attention because of their low cost. In contrast to the rigid coplanar structure of fused ring molecules, slightly rotating ring molecules can lead to different energy distortions, which strongly affect the intramolecular electron transport and thus affect the device performance.
Recently, Prof. Shaoking Zhang replaced the 2-ethylhexyl side chain of A4T-16 with 3-ethylhexyl to synthesize the new acceptor A4T-3, an efficient fully fused ring acceptor previously described. In contrast, the 3-ethylheptyl substituent had a less rigid barrier, allowing A4T-3 to have a more planar structure.
Temperature-dependent mobility results indicated that A4T-3 exhibited less intramolecular energy perturbation than A4T-16, resulting in a more uniform surface electrostatic distribution. Therefore, A4T-3 showed a low barrier for intramolecular electron transport and high electron mobility.
At the same time, the low electrostatic potential of the end group of A4T-3 led to less intermolecular interaction with the donor, which could reduce the non-equilibrium radiant energy loss. When a neat ring polymer, PTVT-T, is used as the donor material, the photovoltaic performance of the A4T-3 based device is significantly improved compared to A4T-16 with a power conversion efficiency of 14.26%.
Note that this is the highest value for organic solar cells when both the donor and acceptor are non-composite ring materials. The cost evaluation shows that the material cost of the PTVT-T:A4T-3 composite is much lower than other high-performance composites, making it an ideal photoactive material without an integrated ring for application-oriented OSC.
The study was published in the journal Science China Chemistry .
More information: Chenyi Yang et al., Reduced Energy Efficiency Enables More Than 14% Efficiency in Ring Donor-Acceptor-Based Organic Solar Cells, Science China Chemistry (2022). doi: 10.1007/s11426-022-1449-4
Citation: Reduced Energy Disorder Enables Over 14% Efficiency in Organic Solar Cells (2023 February 15) February 19, 2023 https://phys.org/news/2023-02-energetic-disorder-enables-efficient-solar website. HTML
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