Science News: 2022 Nat. Energy (IF 67.439), How Oligomer Strategies can Improve Organic Solar Cell Efficiency and Stability
The conversion efficiency of organic solar cells (OSCs) has reached above 19%. However, the combination of high efficiency and long-term stability remains a significant challenge for commercialization. The researchers published a study in Nature Energy (IF 67.439) in 2022. In this study, a series of oligomer acceptors are constructed using Y6-analogue and 2,2′-bithiophene unit to study the effect of molecular size and packing properties on photovoltaic performance. Molecular packing characteristics refer to the arrangement and interactions of molecules in the material, which can affect the physical and chemical properties of the material.
The thermal properties, crystalline behaviors, and molecular packing were modified by changing the molecular chain length and optimal microstructure and a more stable morphology were achieved in blend films. This change can improve the performance and durability of the material. The results showed that:
- Binary OSCs based on oligomer acceptors achieved over 15% efficiency and an extrapolated T80 lifetime over 25,000 h.
- This work emphasizes the importance of the oligomer strategy in adjusting molecular packing behaviors and blend morphology, providing a new type of non-fullerene acceptors for stable and efficient OSC development.
In this study, oligomeric acceptors were used to modify the molecular chain length, thereby improving the efficiency and lifetime of organic solar cells. This approach may help to improve the commercialization potential of organic solar cells.
Synthesis route of OY1-OY4 and POY. Compound 1 and γ-ICBr can be synthesized according to published literatures.
Device performance of OY1–OY4 and POY a,b, J–V characteristics (a) and EQE spectra (b) of the optimized OSCs measured under AM 1.5 G illumination (100 mW cm⁻²). c, Histogram of PCE values for OSCs based on different acceptors, fitted with Gaussian distributions (solid lines).
c, PCE in the course of 1,000 hours light exposure in N2 atmosphere of PBDB-T: OY3, under the same conditions as above. The dashed line corresponds to the linear fitting result from 200 h to 1,000 h, partly excluding the influence of burn-in loss. The error bar and corresponding centre represents the standard deviation (n = 8) and the mean stability. d, PCEs and photo-stabilities of OSCs from previous studies and this work.
Key Word: organic solar cell, oligomer acceptor
Article link: https://doi.org/10.1038/s41560-022-01155-x