Organic solar cells hit a certified 20.65% efficiency in the lab

Electrons have to leave a solar cell through a layer most people never hear about. In organic solar cells, that exit layer has been difficult to tune, and a team led by Jia Yao and Rui Zhang reports a way to do it. Their paper, published online on 20 October 2026 in Nature Energy, describes 20.65% certified efficiency for binary organic solar cells, meaning cells whose light-absorbing layer blends two materials.

The layer in question is the cathode interlayer, a thin film placed between the light-absorbing layer and the metal electrode. Its performance depends on how its molecules are oriented: the electrical dipoles in the layer only work as intended when the molecules stand in the right direction, and the authors note that this orientation has remained hard to control. Their answer is a stepwise solvent treatment, applied in stages, that produces a vertically aligned interlayer.

The figure is certified, meaning it has been checked by a third party, but it concerns cells made in the lab. No outdoor test and no full-module measurement is described in the reported result. A separate paper in Nature Materials reports a different route: a hybrid cathode interfacial layer, called AZnO-F3N, that delivers 21.0% efficiency along with, the authors say, excellent stability. That figure is not described as certified, so the two numbers are not directly comparable.

For organic photovoltaics, the immediate beneficiaries are the research groups that can reproduce a stepwise process and push the interlayer further. Factories and buyers are further away: neither paper gives a commercial timeline, a production partner or a cost, and no product on sale is mentioned. What changes now is narrower but concrete: the orientation of one layer, once hard to control, can be set on purpose.