Chinese research team successfully prepares high-efficiency flexible solar cells
On February 11th, it was learned from Huazhong University of Science and Technology that the team of Professor Shao Ming and Professor Zhang Xinliang from the Wuhan Optoelectronics National Research Center of the university has successfully achieved a stretchable solar cell that combines excellent mechanical flexibility and high photoelectric conversion efficiency, providing an ideal power supply solution for wearable devices. Recently, the research result "Organic solar cells with mechanical strength and stretchability achieved by small molecule receptor plasticization" was published in Science.
In the study, the team designed a novel small molecule receptor material BTP-Si4. Unlike the widely used fullerene and non fullerene small molecule receptors, this receptor material exhibits a unique "plasticizing" effect. It can penetrate a large proportion into the amorphous region of the active layer polymer donor, increase the "free volume" of the polymer segments, facilitate the sliding and reorientation of the polymer segments under external stress, and effectively reduce the crystallinity of the overall photoactive layer film, thereby greatly improving the mechanical tensile properties of the film.
Meanwhile, the receptor molecule can maintain efficient charge transfer through tight 3D stacking and has high electron mobility. Based on the blend active layer film of the small molecule receptor and the ultra-high ductility polymer donor (PNTB6 Cl), the team successfully prepared a highly efficient (photovoltaic conversion efficiency exceeding 16%) flexible/stretchable solar cell. The device can withstand up to 95.5% ultimate tensile deformation, far exceeding various types of flexible solar cells previously reported.
This device can perfectly conform to human skin, even when attached to highly deformed joints such as fingers, wrists, knees, etc., the device can still function normally. It can also provide sufficient driving capability for most wearable electronic devices under outdoor and indoor light exposure.
This study also overturns the traditional view that in order to achieve high photoelectric conversion efficiency and high carrier mobility, it is necessary to adopt a rigid planar molecular skeleton and obtain a highly crystalline thin film, which usually inevitably leads to a decrease in the stretchability of the thin film. This research work reveals a universal design principle for organic semiconductors - through the rational design of small molecule receptor side chains, their interaction with polymer donors can be regulated, while achieving high photoelectric conversion efficiency and excellent mechanical properties.
This study overcomes the inherent brittleness problem of the absorber layer in batteries through innovative material combinations, demonstrating the unique role of small molecule acceptors in enhancing ductility and maintaining electron mobility, "commented the editor of the journal Science.