Angle-independent hot carrier generation and collection using transparent conducting oxides.

Abstract

When high-energy photons are absorbed in a semiconductor or metal, electrons and holes are generated with excess kinetic energy, so-called hot carriers. This extra energy is dissipated, for example, by phonon emission, which results in sample heating. Recovery of hot carriers is important for detectors, sensors, and power convertors; however, the design and implementation of these devices is difficult due to strict requirements on the device geometry, angle of illumination, and incident photon wavelength. Here, we present for the first time a simple, angle-independent device based on transparent conducting electrodes that allows for the generation and collection of hot carriers. We show experimental photocurrent generation from both monochromatic and broadband light sources, show uniform absorption for incident illumination at up to 60° from the surface normal, and find an expected open-circuit voltage in the range 1.5-3.0 V. Under solar illumination, the device is 1 order of magnitude more efficient than previous metal-insulator-metal designs, and power conversion efficiencies >10% are predicted with optimized structures. This approach opens the door to new hot carrier collection devices and detectors based on transparent conducting electrodes.