Nat. Commun.: Research teams of PolyU Gang Li & UCLA Yang Yang Employ Innovative Strategy for High Efficiency (19.31%) and Reduce Non-radiative Recombination Loss in Binary Organic Solar Cells
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Highlights
- Research teams led by Gang Li from Hong Kong Polytechnic University and Yang Yang from UCLA have developed a non-monotonic intermediate state control strategy to simultaneously optimize the crystallization kinetics and energy losses of non-fullerene organic solar cells.
- This strategy employs 1,3,5-trichlorobenzene as a crystallization regulator, inducing a non-monotonic intermediate state transition that first enhances and then relaxes the morphology of the active layer.
- In PM6:BTP-eC9 organic solar cells, this strategy achieved an efficiency of 19.31%. In PM1:BTP-eC9 organic solar cells, non-radiative recombination energy losses were reduced to 0.168 eV (19.10% efficiency), offering significant potential for future research in organic solar cells.
Research Background
Non-fullerene acceptor organic solar cells represent the forefront of this field, benefiting from innovations in material and morphology control. Suppressing non-radiative recombination losses and improving performance are at the core of organic solar cell research. Traditional solvent additives like 1,8-diiodooctane, while capable of enhancing the crystallinity of non-fullerene acceptors, can also lead to excessive aggregation of acceptors, increasing non-radiative recombination losses. Developing new morphology control techniques that simultaneously optimize the self-assembly of donor and acceptor materials and reduce non-radiative recombination has become an urgent priority. This study utilizes 1,3,5-trichlorobenzene as a crystallization modulator and achieves a non-monotonic intermediate state transition by controlling the film formation process, leading to an initial aggregation followed by relaxation. This approach aims to simultaneously enhance the efficiency of organic solar cells while reducing non-radiative recombination losses.
Research Results
The research team of this study has developed a non-monotonic intermediate state control strategy. By applying this strategy to PM6:BTP-eC9 binary organic solar cells, they achieved an efficiency of 19.31% (certified at 18.93%), setting a new record for binary organic solar cells. Simultaneously, the PM6:BTP-eC9 system exhibited very low non-radiative recombination energy losses, measuring only 0.190 eV. In PM1:BTP-eC9 organic solar cells, they further achieved an efficiency of 19.10% and a non-radiative recombination loss of 0.168 eV. Additionally, this strategy demonstrated good universality, outperforming conventional 1,8-diiodooctane treatment in multiple organic solar cell systems. The strategy not only enhanced efficiency but also improved light stability. This study offers a new pathway to reduce non-radiative recombination losses in organic solar cells and unleash the potential of emerging non-fullerene materials.
Research Methods
- The interaction between trichlorobenzene and the active material was studied using techniques such as differential scanning calorimetry, thermogravimetric analysis, and in-situ grazing-incidence wide-angle X-ray scattering (GIWAXS).
- The impact of trichlorobenzene treatment on the performance of organic solar cells was tested.
- Charge transport and recombination dynamics after trichlorobenzene treatment were investigated using methods such as space charge limited current
(SCLC) method and transient photovoltage (TPV) measurement.
- Trichlorobenzene-induced non-monotonic intermediate state transitions were studied through in situ UV-Vis reflection spectroscopy and GIWAXS.
- The various losses in organic solar cells before and after trichlorobenzene treatment were calculated and analyzed.
- The universality of this method was verified in multiple organic solar cell systems.
- The influence of trichlorobenzene treatment on the light stability of organic solar cells was assessed.
Conclusion
A new strategy was employed in the research, using 1,3,5-trichlorobenzene to optimize organic solar cells. This strategy improved the film crystallization process, controlled molecular aggregation, successfully enhanced the efficiency of organic solar cells, and reduced non-radiative recombination losses, offering potential for future research.
Fig. 2 Device performance of OSCs with DIO and TCB processing.
Fig. 4 In situ UV-vis characterization.
Fig. 6 The generality of TCB and the analysis of V_{oc} loss as well as light stability.
Keywords：
organic solar cell
Recommended Instruments:Solar Simulator、QE-R Quantum Efficiency Measurement System
Article Link：
https://www.nature.com/articles/s41467-023-37526-5
