  The high performance of hybrid perovskite based devices is attributed to its
excellent bulk-transport properties. However, carrier dynamics, especially at
the metal-perovskite interface, and its influence on device operation are not
widely understood. This work presents the dominant transport mechanisms in
methylammonium lead iodide (MAPbI3) perovskite-based asymmetric metal-electrode
lateral devices. The device operation is studied with inter-electrode lengths
varying from 4 {\mu}m to 120 {\mu}m. Device characteristics indicate distinct
ohmic and space-charge limited current (SCLC) regimes that are controlled by
the inter-electrode length and applied bias. The electric-potential mapping
using Kelvin-Probe microscopy across the device indicates minimal ion-screening
effects and the presence of a transport barrier at the metal-MAPbI3 junction.
Further, photocurrent imaging of the channel using near-field
excitation-scanning microscopy reveals dominant recombination and
charge-separation zones. These lateral devices exhibit photodetector
characteristics with a responsivity of about 51 mA/W in self-powered mode and
5.2 A/W at 5 V bias, in short-channel devices (4 {\mu}m). The low device
capacitance enables a fast light-switching response of ~12 ns.
