Illuminating the Future: How Light and Heat Team Up to Generate Electricity in Nanomaterials

Posted by Quantum Server Networks • August 2025

Nanoscale imaging reveals photocurrent effects

In a major stride toward understanding how electricity is generated at the smallest scales, scientists at the University of California, Riverside have developed a new imaging method that reveals the inner workings of how light and heat produce electric current in nanomaterials. Their findings, published in Science Advances, could significantly enhance the design of optoelectronic devices—from solar panels to next-generation light sensors and photodetectors.

Photovoltaic vs. Photothermoelectric: A Delicate Dance

The study, led by Associate Professors Ming Liu and Ruoxue Yan, focused on distinguishing two key processes by which light energy is converted into electrical energy at the nanoscale:

First is the photovoltaic (PV) effect, a well-known mechanism wherein incoming photons knock electrons loose in a semiconductor, generating current. Second is the photothermoelectric (PTE) effect, a more subtle process in which light-induced heat energizes electrons, causing them to migrate toward cooler regions and produce current that can oppose or complement the PV-generated current.

"We knew both effects were happening, but we couldn’t quantify or separate them spatially—until now," said Liu. The team’s new technique finally unveils how these mechanisms interact and compete in real-world nanodevices.

Molybdenum Disulfide Meets Gold: A 2D–3D Quantum Playground

To test their imaging method, the team used nanodevices made of molybdenum disulfide (MoS₂)—a 2D semiconductor—paired with 3D gold electrodes. MoS₂, just a few atoms thick, has become a superstar material in nanotechnology due to its exceptional electronic and optical properties.

Using a sophisticated setup that funnels light through the tip of an atomic force microscope, researchers scanned these nanostructures with nanoscale precision. They discovered that while the PV effect dominates at the MoS₂–gold interface as expected, the PTE effect unexpectedly extends much deeper into the semiconductor, influencing larger areas than previously thought.

Tuning Heat for Better Electronics

In a surprising twist, the team found that adding a thin layer of hexagonal boron nitride (h-BN) could redirect heat sideways within the MoS₂ layer. This boosted the PTE effect by aligning temperature gradients with material responses—effectively enhancing electricity generation by using heat flow as a design parameter rather than an obstacle.

"Normally, in electronics we try to isolate or confine heat," said first author Da Xu. "But in this case, allowing it to spread strategically helps generate more current."

Advanced Imaging and Analysis

To achieve this level of insight, the researchers devised a unique analytical approach based on multi-order harmonic analysis, allowing them to decompose photocurrent signals by varying the tip-to-sample distance. This is the first time that spatial contributions from PV and PTE effects have been successfully isolated in real space at the nanoscale.

Such analysis is crucial as photodetectors and optoelectronic devices continue to shrink. Understanding how heat and light interact at tiny scales will allow engineers to design better fiber-optic systems, sensors, and energy harvesters that perform optimally despite thermal fluctuations.

Implications for Future Technologies

This study could pave the way for more efficient and miniaturized energy devices—those that don't just capture light, but also intelligently exploit the heat that typically goes to waste. For solar energy, wearable electronics, and quantum sensors, leveraging both the PV and PTE effects opens new frontiers in performance and efficiency.

As Liu concluded, "We're just beginning to uncover how light, heat, and electricity interact in these extraordinary materials. There’s a lot more to discover."

🔗 Read the full article: https://phys.org/news/2025-07-imaging-method-reveals-generate-electricity.html

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#Nanomaterials #Photovoltaics #Photothermoelectric #MoS2 #HeatFlow #Optoelectronics #NanoscaleImaging #QuantumDevices #2DMaterials #SolarTechnology #ScientificBreakthrough #QuantumServerNetworks #PWmat

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