In-situ solid-phase anion-exchange full-color perovskite light-emitting devices

Abstract

Perovskite materials can realize the transition from green light to full-visible light spectrum by halogen anion exchange. Here, we designed an in-situ solid-phase anion-exchange method combined with inkjet printing to achieve full-color perovskite quantum dot light-emitting diodes (PeQD-LEDs). It was revealed that, in addition to the concentration, the anion-exchange rate was affected by the dielectric constant of the anion-exchange medium solvent. Without destroying the PeQD film, the higher the dielectric constant of the solvent, the faster the reaction rate. And at the same time, the solvent with higher dielectric constant will cause more defects, so the morphology, structure and properties of the perovskite films varied with solvents. The chain length of amine salts in anion-exchange medium solute also played a key role in the stability of electroluminescence spectra. The obtained blue-light devices had a maximum EQE of 4.6% at 481 nm and 6.6% at 493 nm prepared by spin-coating. For inkjet printing, instead of printing red-, green- and blue-luminescent materials, we printed halogen-containing materials to achieve the in-situ solid-phase anion-exchange with underlying PeQDs, and the inkjet-printed full-color device showed the current efficiency of 0.78 cd A⁻¹. The method to achieve full-color devices by inkjet-printing halogen-containing materials can not only simplify the process, but also broaden the range of material selection, making the ink preparation more selective.