Flexible inorganic–organic thin film phosphors by ALD/MLD

Abstract

Inorganic–organic europium-based hybrid materials have good luminescent properties and play a key role in many important optical applications, such as nanosized phosphorescent and optoelectronic devices. Here we demonstrate the feasibility and potential benefits of synthesizing such materials with a direct deposition method with atomic/molecular level precision using the emerging atomic layer deposition/molecular layer deposition (ALD/MLD) technique. Such a process allows for fundamentally new types of highly uniform and conformal hybrid inorganic–organic thin films by alternating exposures of inorganic and organic reactants on flexible/sensitive/nanostructured surfaces. We employ Eu(thd)₃ and 3,5-pyridinedicarboxylic acid as precursors and deposit the films on a variety of substrate materials in the temperature range from 240 to 400 °C. The appreciably fast self-limiting surface reactions yield thin films with high luminescence intensities. We foresee that our Eu-hybrid thin-film phosphors grown by ALD/MLD could be exciting new phosphor materials in applications where ultrathin luminescent coatings on flexible and/or nanostructured surfaces are needed.