Hong Kong University of Science and Technology demonstrated 10.8 % efficiency with 10 different mixtures


In a paper published in Nature Communications, a research team from Hong Kong University of Science and Technology led by He Yan and researchers from North Carolina State University demonstrate that temperature-controlled aggregation in a family of new semi-conducting polymers is the key to creating highly efficient organic solar cells that can be mass produced more cheaply. They also show that record efficiencies of up to 10.8% - compared to the currently published 9.8% - are achievable with the substitution of numerous fullerenes.

Polymer solar cells are a delicately controlled mixture of a polymer donor and a fullerene acceptor. The cell is created by adding a solvent to the polymer and fullerene until the mixture becomes a liquid, then spreading the liquid thinly onto a surface. As the solvent evaporates, the thin layer solidifies, with the donor material hardening into tiny, highly ordered "clumps" that are connected by other, disordered donor molecules, and the acceptor weaving around them.

North Carolina State physicist Harald Ade and postdoctoral researcher Wei Ma had previously studied the morphology of solar cells and discovered that the size scale of the clumps within the donor layer and the aggregation - or interaction between neighboring molecules within the layers - were the main drivers of solar cell efficiency. Harald Ade said that temperature affected the aggregation and morphology of these solar cells, it allowed the chemists more freedom to play with different chemical compositions in the active layer. Meanwhile, Prof. Yan's team demonstrated 10% efficiency with 10 different mixtures, and in thicker films. Therefore, these solar cells could be compatible with existing methods of mass production, such as slot die casting and roll-to-roll processing similar to newspaper printing.

They hope that these findings will allow others to experiment with different polymer: fullerene blends, further increasing the efficiency of solar cells, decreasing their production costs and leading to a commercially viable alternative source of energy.

Prof. Henry Yan from Hong Kong University of Science and Technology, who is an expert in organic electronics such as organic solar cells, organic transistors and organic light-emitting diodes. Given that the research of organic solar cells is getting more attention, Professor Henry Yan selected Enlitech’s QE-R Total Quantum Efficiency Solutions for Solar Cells as their research tool.

QE-R is a high- performance measurement system of Quantum Efficiency/Spectral Response/ IPCE for a wide variety of solar cells, it is designed for universities, research institutes and manufacturers to do research & development and quality control in production. With professional optical design, unique DSP dual-phase lock-in amplifiers and excellent hardware capabilities, it can provide user accurate measurement results and high repeatability. The high-intensity monochromatic light which enables a higher signal to noise ratio and shortens the measuring time. Furthermore, QE-R provides the ability of outstanding customization and integration which can exactly match user’s needs, making it a truly multi-functional instrument.

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