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Abstract Zero‐dimensional (0D) organic metal halide hybrids (OMHHs) have recently emerged as a new class of light emitting materials with exceptional color tunability. While near‐unity photoluminescence quantum efficiencies (PLQEs) are routinely obtained for a large number of 0D OMHHs, it remains challenging to apply them as emitter for electrically driven light emitting diodes (LEDs), largely due to the low conductivity of wide bandgap organic cations. Here, the development of a new OMHH, triphenyl(9‐phenyl‐9H‐carbazol‐3‐yl) phosphonium antimony bromide (TPPcarzSbBr₄), as emitter for efficient LEDs, which consists of semiconducting organic cations (TPPcarz⁺) and light emitting antimony bromide anions (Sb₂Br₈²⁻), is reported. By replacing one of the phenyl groups in a well‐known tetraphenylphosphonium cation (TPP⁺) with an electroactive phenylcarbazole group, a semiconducting TPPcarz⁺cation is developed for the preparation of red emitting 0D TPPcarzSbBr₄single crystals with a high PLQE of 93.8%. With solution processed TPPcarzSbBr₄thin films (PLQE of 86.1%) as light emitting layer, red LEDs are fabricated to exhibit an external quantum efficiency (EQE) of 5.12%, a peak luminance of 5957 cd m⁻², and a current efficiency of 14.2 cd A⁻¹, which are the best values reported to date for electroluminescence devices based on 0D OMHHs. 

Light emitting diodes (LEDs) have wide applications from fullcolor displays to solid‐state lighting. Numerous types of luminescent materials have been explored for LEDs, ranging from inorganic semiconductors to metal complexes and quantum dots. Despite the rapid pace of development, LEDs have not achieved their full potentials in terms of performance and cost efficiency. Identifying new eco‐friendly materials for LEDs is of great interest. Recently, metal halide perovskites and perovskite‐related hybrid materials have emerged as new generation luminescent materials with unique optoelectronic properties. Here, some of our recent development of LEDs based on metal halide perovskites and perovskite‐related materials will be discussed.