The extrinsic photoresponse is the true signal processing time (detector speed) of the entire device with highest relevance for real applications. The basic concepts for its experimental determination are detailed in Box 1. A laser with a pulse length much shorter than the response time excites the photoactive material to assess the rise and fall times, limited by the slowest mechanism present. Possible limitations are the RC time, drift / transit time and diffusion time. The RC time 𝑡 𝑅𝐶 is the product of the device capacitance and the device resistance, which is omnipresent in every electrical component. included in these fundamental three components are the carrier injection time at the electrode and the transfer time between two materials in a heterostructure or even between two layers in a multilayer. The injection time or electrode-material transfer time is found indirectly in the RC time in form of the contact resistance whereas the material-transfer time is part of the drift or diffusion time, depending on the depletion.