The team, led by associate professors Ming Liu and Ruoxue Yan, used atomic-force microscopy in combination with light excitation and harmonic analysis to map out how two energy conversion effects—photovoltaic and photothermoelectric—coexist within next-gen materials like molybdenum disulfide (MoS₂). Said Liu, “Before now, we knew both effects were happening, but we couldn’t see how much each one contributed and how they spatially distribute. With our new technique, we can finally tell them apart and understand how they work together. That opens new ways to design better devices.”
The photovoltaic effect, common in commercial solar panels, converts photons into electric current at semiconductor junctions. The photothermoelectric effect, by contrast, relies on heat gradients within the material to move charge. This technique isolates both mechanisms on the nanoscale, giving researchers a more detailed understanding of how they overlap or interfere depending on material structure and design.
Their experiments revealed that in ultrathin MoS₂ devices paired with gold electrodes, the heat-driven photothermoelectric effect reaches much farther across the material than previously assumed. This finding directly challenges current engineering assumptions that treat heat as a byproduct rather than an asset in solar design.
One of the most impactful findings came from adjusting thermal flow using a thin insulating layer of hexagonal boron nitride. Rather than letting heat dissipate outward, this layer directed thermal energy sideways through the MoS₂, enhancing temperature gradients that increased overall electricity output. That’s a significant departure from the industry norm of minimizing heat in electronic devices.
These insights open up design opportunities across multiple sectors. For solar energy developers, the ability to capture both light and thermal energy within the same material stack points to potential hybrid systems with higher total efficiency. In telecommunications, where miniaturization and speed are key, improved understanding of thermal effects could enhance photodetector performance in fiber-optic infrastructure.
Beyond renewable energy and communications, the new imaging method offers potential benefits for the development of nanoscale sensors, quantum computing hardware, and optical systems—where control over photoelectric interactions is central to functionality. By making it possible to visualize how heat and light jointly contribute to electricity generation, the technique provides manufacturers with the tools to build more efficient, better-targeted devices.
