High performance hybrid near-infrared LEDs using benzenedithiol cross-linked PbS colloidal nanocrystals

We report an all solution-based processing method to produce efficient hybrid polymer–nanocrystal multilayered heterostructures for electroluminescence in the near-infrared (1050–1600 nm). We employ for the first time the benzenedithiol cross-linking method to produce high-quality PbS nanocrystalline films acting both as an electron-transporting and electroluminescent layer within a near-infrared light emitting diode (LED) architecture. Due to the large volume of nanocrystals and the good carrier-transport properties within the cross-linked nanocrystalline films, this device architecture yields high emission powers and good quantum efficiencies. In contrast, using ethanedithiol cross-linking molecules results in nanocrystalline films with low photo- and electro-luminescence efficiencies.

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► PbS nanocrystalline films and polymers are used to form hybrid heterostructures.
► Ethanedithiol (EDT) and benzenedithiol (BDT) ligand-exchange treatments are compared.
► The BDT treatment provides a mobility barrier keeping excitons at the interface.
► The lower conductivity in the BDT-treated films also preserves the carrier balance.
► This provides superior hybrid near-infrared LEDs using solution-based processing.