Photodetector technologies based on emerging semiconductors—for example, organic semiconductors, halide perovskites, quantum dots, low-dimensional semiconductors and metal oxides—hold considerable promise for next-generation optoelectronics. However, the breadth and multidisciplinarity of this field, alongside its diverse range of applications, have resulted in inconsistent performance characterization and reporting practices, hindering the effective benchmarking of these technologies. Here we present a consensus among researchers from academia and industry on accurately capturing the key performance metrics of photodetectors based on emerging semiconductors and utilizing the photoelectric effect. We analyse their underlying assumptions, discuss common misunderstandings, and provide guidelines for accurate characterization and reporting. Additionally, we discuss the benchmarking of these photodetector technologies with respect to diverse applications. We expect that these comprehensive guidelines for characterization, reporting and benchmarking will accelerate and streamline further advancements in the field, propelling emerging photodetector technologies towards their full potential.