Photophysical properties of materials for high-speed photodetection

Fast-response optical sensing across the electromagnetic spectrum is an enabler of quantum systems, 3D machine vision and augmented reality, yet existing technologies are not optimized for infrared sensing. Trade-offs among characteristics such as speed, efficiency, noise, spectral detection range and cost motivate the research community to develop nanostructured sensing materials that provide operation from visible to infrared wavelengths with seamless integration. As efforts are made to advance the combined gain and bandwidth of devices, a clear understanding of physical mechanisms underlying the dynamics of charge carriers, with a particular focus on speed-limiting processes, is of high priority. In this Review, we provide an account of the photophysical attributes of active materials and their impact on optical sensor performance, focusing on the interplay between temporal and peak response to pulsed light of varying durations. We identify performance-limiting processes and directions for future progress in developing materials and device architectures that realize high-speed photodetection. Developing photodetectors that work across the electromagnetic spectrum remains a challenge, and there are many trade-offs to be considered, including speed, efficiency, noise, spectral detection range and cost. This Review discusses the photophysical attributes of the active materials that define the interrelated aspects of response amplitude and temporal dynamics in photodetectors.