In light-emitting diodes (LEDs), the charge injection rate is critical to device performance, but it is generally limited by resistance–capacitance (RC) time constants to nanosecond or longer timescales. While optical excitation can produce carriers on femtosecond timescales, it inherently generates excitons, complicating the study of individual charge carriers. Here, we present an infrared (IR) optical control strategy that enables ultrafast electrical charge injection in operational perovskite LEDs (PeLEDs). Under electrical bias, space charge naturally accumulates at device interfaces, and an ultrafast IR pulse can modulate this interfacial charge distribution. This accelerates the injection of charges into the emissive perovskite layer on femtosecond timescales—far faster than intrinsic electronic response times—and thereby enhances electroluminescence.

To probe this process, we combine electrical injection and optical excitation in an operando electrical pump–IR push–visible probe spectroscopy setup. Using this technique, we observe the rapid emergence of band-edge carriers in the perovskite layer immediately following the IR pulse. Time-resolved electroluminescence measurements confirm that these IR-injected carriers directly enhance radiative recombination in the PeLED. Modified device architectures with selective charge-blocking layers show that the injected carriers originate predominantly from the electron-transport layer interface, demonstrating polarity-selective control of electrical injection.

We demonstrate that in halide perovskite devices, charge injection is governed not only by energy-level alignment but also by material-specific interfacial properties. Unlike conventional electrical injection, which relies on thermal occupation of interfacial states, an infrared (IR) optical pulse can transiently enhance carrier injection by manipulating the space-charge population accumulated near an injection barrier. Absorption of IR photons promotes carriers into higher-energy or more strongly coupled interfacial states, enabling transfer into the perovskite emissive layer while partially bypassing limitations imposed by barrier height, width, and electronic coupling. Our results reveal that charge injection is strongly influenced by material-level interfacial factors, including space-charge distribution, interfacial dipoles, and electronic coupling, providing new strategies for optical control of carrier transport and the design of faster, more efficient perovskite optoelectronic and quantum devices.