Excitation power dependence and loss of photonic energy conversion

Photonic energy conversion of photodiodes has been investigated as functions of the excitation wavelength and power. We conducted detailed characterization under monochromatic light to identify the loss mechanisms that are critical for its use as a laser power converter. The short-circuit current rises linearly with increasing excitation power, but the open-circuit voltage shows two regions with varying slopes due to Joule heating. At higher excitation power densities, thermal effects significantly impact the current-voltage characteristics, resulting in peak conversion efficiency at a specific excitation power density. These photovoltaic characteristics influenced by Joule heating were compared for direct- and indirect-bandgap photodiodes.