Researchers at the Hong Kong Polytechnic University have developed a binary organic solar cell (OSC) with a record power conversion efficiency of 19.31%. They devised a non-monotonic interstitial manipulation strategy to reduce non-radiative recombination loss and improve efficiency.
Now, researchers at the Hong Kong Polytechnic University have achieved a breakthrough PCE of 19.31 percent for binary OSCs with one donor and one acceptor in the photoactive layer. The research team came up with a new OSC morphology-regulating technique to increase cell efficiency and stability using 1,3,5-trichlorobenzene as a crystallization regulator.
They developed a non-monotonic intermediate state Manipulation (ISM) strategy to manipulate bulk heterojunction (BHJ) OSC morphology and simultaneously optimize the crystallization dynamics and energy dissipation of non-fullerene OSCs.
In contrast to the strategy of using traditional solvent additives, which is based on excessive molecular aggregation in films, the ISM strategy promotes more ordered molecular stacking and more favorable molecular aggregation, the researchers explain. As a result, the PCE increased considerably and the unwanted non-radiative recombination loss, which lowers the efficiency of light production and increases heat loss, was reduced.
It took the research team about two years to develop a non-monotonic ISM strategy.
“The challenges in the research stemmed from existing additive-based morphology benchmark control methods that suffer from non-radiative recombination loss, which lowers the open-circuit voltage from excessive aggregation,” says Li Gang, professor of energy conversion technology. The Hong Kong Polytechnic.
According to Li, the new discovery is likely to create “tremendous opportunities” for applications such as portable electronics and building-integrated solar power. While OSC technology is still in its infancy, new applications are expected as low-cost single-junction OSCs exceed the 20% PCE threshold and achieve more stable performance to complement their unique advantages such as flexibility, transparency, flexibility, lightness, and tunable color.
“The latest study shows a record low non-radiative recombination loss of 0.168 eV in a binary OSC with a PCE of more than 19 percent,” says Li. “This is a very encouraging result for the long-term OSC research I’ve been doing over the past two decades.”
The researchers described their findings in “19.3% Binary Organic Solar Cell with Low Nonradiative Recombination Enabled by Nonmonotonic Interstitial Transition,” published recently Nature communication.