Chinese Researchers Develop Laser Receiver to Power Drones Mid-Flight

The PLC-TE Tandem Device

The core of the system is a perovskite laser cell-thermoelectric (PLC-TE) tandem device. This receiver is based on solar cell design but is optimized for laser light rather than solar radiation. The device utilizes perovskite, a synthetic compound with a crystalline structure that captures more wavelengths of the light spectrum than silicon, to convert laser light directly into electrical energy.

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To address energy loss in the form of heat, the researchers added a thermoelectric layer. This layer captures heat and converts it into electricity by utilizing the temperature difference between the warm side exposed to the laser and the cooler opposite side. According to the researchers, the system achieved an energy conversion efficiency of 38.49% when illuminated by a green laser. This figure exceeds the 34% peak results for perovskite-silicon tandem cells recorded by the U.S. Department of Energy.

Overcoming Thermal Challenges

Heat management emerged as a primary obstacle during development. Senior author Jianhua Han stated that thermal cameras recorded temperatures between 80 and 90 degrees Celsius during tests with a high-power laser, which reduced the device’s efficiency.

To mitigate this, the team integrated specialized nanocrystals with low thermal conductivity into the design. These nanocrystals act as a thermal barrier to slow the transfer of heat through the receiver. Additionally, when the receiver was attached to a drone model, researchers created airflow channels within the wings. The airflow generated by the propeller helped cool the cold side of the thermoelectric layer, further maximizing the conversion of heat to electricity.

Testing and Future Applications

The technology has currently been proven as a principle of energy conversion and has not yet undergone a real flight test. In laboratory experiments, the receiver was placed under the wing of a stationary drone model, where the laser provided enough energy to spin the propeller. Researchers noted that moving the technology from the lab to the field is an engineering challenge that requires solving issues regarding power stability, operational safety, and the development of real-time tracking systems to precisely target the PLC-TE receiver on a moving aircraft.

The team plans to conduct future tests using a real lightweight drone in outdoor environments. Han identified several key areas where this technology could be applied, including:

• Disaster relief and monitoring
• Forest inspection
• Logistics and package delivery
• Reconnaissance

The potential for extended flight times is particularly significant for unmanned aerial vehicles (UAVs). For context, the AeroVironment RQ-11 Raven, a common hand-launched UAV, typically has a maximum flight time of 60 to 90 minutes before requiring a charge. Laser power could allow reconnaissance and weapons-carrying UAVs to operate in environments where they are currently restricted by refueling requirements.