China Unleashes Solar Tech With Triple Power And A Record 67% Efficiency

In a major step forward for solar energy technology, a group of Chinese scientists has developed a new type of organic photothermal cocrystal that dramatically improves the performance of solar thermoelectric generators (STEGs).

Solar thermoelectric generators have long relied on materials capable of converting sunlight into heat to create the temperature differences necessary for electrical generation. While traditional materials like carbon-based compounds and metal oxides have shown promise, a new class of organic radical photothermal cocrystals is setting a new benchmark.

The breakthrough comes from a collaborative research effort among scientists at Nanchang University, Soochow University, and Nanjing University. Their innovation centers on coronene-Br?NDA (CBC)—a cocrystal synthesized from coronene and an open-shell radical molecule called Br?NDA. These molecules spontaneously assemble into highly crystalline, needle-like microrods via a simple, solution-based method. The result is a material with exceptional light absorption and heat conversion properties.

“Under 808 nm laser irradiation at 0.367 W cm², the prepared cocrystal reached an equilibrium temperature of 86 degrees Celsius within seconds,” the team reported, citing a photothermal conversion efficiency (PCE) of 67.2%—a performance level that outpaces many previously documented organic photothermal materials.

Lead author Sheng Zhuo, a PhD candidate at Nanjing University, emphasized the significance of this performance: the cocrystal not only heats up rapidly but maintains high thermal stability and consistency over repeated heating and cooling cycles.

To confirm the cocrystal’s internal behavior, the team conducted advanced structural and spectroscopic analyses, including XRD, SAED, UV-Vis absorption, PL, FT-IR, and solid-state NMR. The data revealed robust charge transfer interactions between the components, as well as light absorption stretching from 350 to 1100 nanometers. The material also exhibited a marked redshift and near-total photoluminescence quenching—signs of efficient energy conversion without radiative loss.

To demonstrate practical applications, the researchers embedded the CBC cocrystal in a transparent resin, creating a photothermal ink. When applied to a thermoelectric generator and exposed to simulated sunlight at double the intensity of natural light, the generator’s surface temperature climbed to 70.3°C (158.54°F), with voltage output jumping to 209 mV—a 375% increase over an uncoated counterpart.

But the implications extend beyond power generation. By modulating a laser beam, the team successfully transmitted encoded messages, such as Morse code, through near-infrared light. This opens doors to futuristic applications in non-contact data transmission, wearable encryption tech, and adaptive electronics.

“A series of sophisticated analyses… provided compelling evidence of strong charge transfer (CT) interaction between COR and Br?NDA,” the team explained.