Photovoltaic Laser Power Conversion Techniques

Photovoltaic laser power conversion techniques harness monochromatic or narrowband optical sources to generate electrical power with high efficiency. They form the core of power-by-light systems, which enable remote, galvanically isolated energy delivery across optical fibres or free-space links. Central to these approaches are semiconductor devices engineered with multiple epitaxial subcells, often employing III–V materials such as GaAs or InGaAs, stacked vertically and interconnected by tunnel junctions. By tailoring the bandgaps and thicknesses of each subcell to the incident laser wavelength, these multijunction architectures minimise entropic and series resistance losses and optimise the external quantum efficiency. Innovations in material systems, including high-bandgap alternatives such as silicon carbide, address intrinsic losses encountered at high power densities. Contemporary research emphasises not only peak conversion efficiencies—surpassing 80% in specialised designs—but also practical aspects such as thermal stability, tolerance to non-uniform beam profiles and scalable device areas. The convergence of advanced epitaxial growth, precision doping profiles and optical management strategies underpins ongoing improvements in power output, voltage scaling and operational robustness, opening pathways to applications in unmanned aerial vehicles, biomedical implants and distributed sensor networks.

Research from Nature Portfolio

A seminal work has demonstrated a six-volt vertically stacked GaAs photovoltaic power converter employing tunnel junctions between subcells to produce output powers above 1 W under monochromatic illumination. The device achieved a peak conversion efficiency above 50% at moderate input power densities, with an operating voltage of 5.5 V–6.0 V. Thickness optimisation of each GaAs subcell, informed by absorption coefficients, and refinement of tunnel-junction design were shown to be critical for enhancing external quantum efficiency and power density. This architecture established a foundational route for high-voltage photovoltaic laser receivers tailored to deliver both elevated voltage and efficiency within compact epitaxial assemblies.

Photovoltaic Laser Power Conversion Techniques publication trend

The graph below shows the total number of articles in photovoltaic laser power conversion techniques across all publications each year (not limited to Nature Index journals).

Technical terms

Photovoltaic laser power converter (PVLPC): A device that converts monochromatic laser light into electrical power using semiconductor p–n junctions configured for a specific optical wavelength.

Multijunction architecture: A stacked assembly of semiconductor subcells with different bandgaps, optimised to sequentially absorb portions of the incident spectrum and improve overall conversion efficiency.

Tunnel junction: A heavily doped p–n junction placed between subcells to provide low-resistance electrical interconnection without impeding optical transmission.

External quantum efficiency (EQE): The ratio of collected charge carriers to incident photons at a given wavelength, reflecting the photon-to-electron conversion effectiveness of a subcell.

Vertical epitaxial heterostructure architecture (VEHSA): A design strategy in which multiple ultrathin semiconductor junctions are grown in sequence on a single crystal substrate to form a monolithic multijunction converter.

References

1. A new path towards ultra-high efficient laser power converters: Silicon carbide-based multijunction devices. Results in Engineering (2024).
2. Beaming power: Photovoltaic laser power converters for power-by-light. Joule (2022).
3. Design and fabrication of six-volt vertically-stacked GaAs photovoltaic power converter. Scientific Reports (2016).
4. Vertical Multi-Junction Laser Power Converters with 61% Efficiency at 30 W Output Power and with Tolerance to Beam Non-Uniformity, Partial Illumination, and Beam Displacement. Photonics (2023).