Tsinghua Researchers Hit 38% Efficiency in Laser-to-Electric Charging for Drones

Researchers from Tsinghua University and the Civil Aviation University of China have developed a tandem device capable of converting green laser light into electricity with 38.49% efficiency. The technology is designed for integration into UAV wings, enabling drones to recharge during flight via laser wireless power transmission (LWPT).

The device, termed a perovskite laser cell-thermoelectric (PLC-TE) tandem, achieved its peak power conversion efficiency (PCE) under 520 nm laser irradiation at an incident power density of 1.2 W·cm⁻². To reach this mark, the team utilized a dual-layer approach: a CsPbBr3 perovskite layer handles direct photoelectric conversion, while a thermoelectric (TE) layer harvests waste heat through the Seebeck effect. To optimize performance, the researchers doped antimony triselenide (Sb2Se3) nanorods into the interface. These nanorods serve as a thermal barrier and improve carrier transport, which reduces non-radiative recombination and allows the device to manage higher power densities without degrading.

The Engineering Challenge

Unmanned Aerial Vehicles (UAVs) are currently constrained by the energy density of onboard batteries, forcing frequent landings for recharging. While laser wireless power transmission offers a way to beam energy over long distances with high precision, the process typically generates intense heat. High-intensity lasers often lead to overheating and material degradation in the receiving cells, creating a significant bottleneck for practical deployment.

Jianhua Han of the Civil Aviation University of China noted that the project aimed to move beyond basic materials science. "Previous studies largely focused on the materials or the device itself," Han said. "We wanted to think beyond the laboratory, to how the system could actually be integrated into an aircraft, cooled during operation, and made compatible with flight. It isn't just a materials science problem; it's an engineering one."

Industry Implications

This efficiency jump is significant when compared to existing benchmarks. The researchers report that the PLC-TE device's efficiency is nearly double the approximately 20% efficiency seen in current DARPA laser power-beaming receivers. By pushing efficiency toward 40%, the system significantly lowers the power requirements for ground-based laser stations and reduces the thermal load on the aircraft's structure.

If this technology can be successfully scaled for outdoor environments, it could fundamentally change the operational profile of UAVs. The ability to recharge in-flight would support permanent surveillance, long-term environmental monitoring, and extended delivery missions by removing the need for drones to return to base for power.

Next Steps

While the laboratory results are promising, the transition to real-world flight environments remains the primary hurdle. Future development will likely focus on the durability of the perovskite layers under varying atmospheric conditions and the scalability of the Sb2Se3 nanorod integration. It remains to be seen how the system performs under the fluctuating power densities and alignment challenges inherent in long-distance outdoor laser transmission.