injectionlimited

Injectionlimited is an adjective used in semiconductor physics and optoelectronics to describe a regime in which the electrical current through a device is limited by the rate at which charge carriers can be injected from the electrodes into the active region, rather than by transport, recombination, or generation inside the material.

In devices such as organic light-emitting diodes, perovskite LEDs, solar cells, and other diodes, the overall current may be governed either by injection at the contacts or by transport through the active layer. When injection is inefficient due to large work-function differences, high interfacial barriers, or poor contact quality, the current becomes injectionlimited. This can yield characteristic current–voltage behaviors that depend strongly on the electrode materials, interfacial layers, and near-contact doping.

Distinctions are commonly made with diffusion-limited or transport-limited regimes. In the injectionlimited regime, improving contact properties—such as choosing better matched electrode work functions, inserting interlayers to facilitate injection, or engineering near-contact doping—often yields the most significant performance gains. Conversely, in diffusion- or transport-limited regimes, enhancements focus on the bulk material conductivity, mobility, or device geometry.

Identification of injection limitation can involve analyzing current–voltage curves, temperature dependence, and device models to separate contact-limited effects from bulk-limited ones. Understanding the regime informs design strategies to optimize efficiency, fill factor, and overall device performance.

See also: injection current, contact resistance, Schottky barrier, diode equation, Ohmic contact.