Rear-Heterojunction GaInP Laser Power Converter with 59% Monochromatic Efficiency at 590 nm

Photonic power converters (PPCs) are devices that convert narrowband light at specific wavelengths into electrical energy based on the photovoltaic effect. They are used in optical power transmission systems, which offer advantages over conventional wire based electrical connections in specific applications. GaInP PPCs show promise for underwater communication and power transfer due to their high bandgap energy, which enables efficient photon conversion in the visible spectrum. In this work, we compare rear-heterojunction and homojunction designs for GaInP PPC devices, focusing on key performance characteristics, such as spectral response, quantum efficiency, open circuit voltage, and monochromatic efficiency. Our findings show that the lower sheet resistance in the n-type layer of the rear-heterojunction device facilitates lateral current spreading, reducing series resistance and allowing for higher irradiances. In addition, the n-type layer enhances open circuit voltage, resulting in superior conversion efficiency. In particular, the rear-heterojunction GaInP PPC achieves a peak spectral response at 590 nm with a monochromatic conversion efficiency of 59.1% at an irradiance of 3.95 W cm-2, compared to a peak efficiency of 56.6% at 600 nm and 1.89 W cm-2 for the homojunction device. Notably, at 530 nm, suitable for underwater applications, the rear-heterojunction PPC achieves an efficiency of 55.5% at 4.20 W cm-2. A detailed loss analysis reveals areas for future improvements in the rear-heterojunction device. These findings provide insights for innovation in photonic power converters, aiming for higher efficiency and broader application versatility.