Efficient Red Light Emitting Diodes Based on a Zero-Dimensional Organic Antimony Halide Hybrid

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 (TPPcarzSbBr(4)), 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 TPPcarzSbBr(4) single crystals with a high PLQE of 93.8%. With solution processed TPPcarzSbBr(4) thin 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.

Automated summary

Zero-dimensional (0D) organic metal halide hybrids (OMHHs) are a new class of light emitting materials with exceptional color tunability. However, their application as emitters for electrically driven light emitting diodes (LEDs) is challenging due to the low conductivity of wide bandgap organic cations. In this study, a new OMHH, triphenyl(9-phenyl-9H-carbazol-3-yl) phosphonium antimony bromide (TPPcarzSbBr(4)), is developed as an efficient emitter for LEDs. Red LEDs fabricated with TPPcarzSbBr(4) thin films as the light emitting layer exhibit the highest reported external quantum efficiency (EQE), peak luminance, and current efficiency among 0D OMHH-based electroluminescence devices.