Stability promoted close-packed quantum dot-AlPO4 glass films with tunable and bimodal luminescence

• Sol–gel AlPO4 glass films as substrates for depositing PbS QDs
• QD-AlPO4 films with tunable and bimodal photoluminescence in near infrared
• Improved photostability of QD-AlPO4 films compared to naked QDs
• Formation of close-packed QD solid systems evidenced by energy transfer

Broadly tunable and multi-emission PbS quantum dot (QD)-solid systems have drawn great attention to the applications of telecommunication, microelectronics and solar cells. Here, we propose a simple and practical method for creation of QD-systems in porous AlPO4 glass film matrix. Tunable and bimodal luminescent films in near infrared are achieved by a layer by layer assembly method with PbS QDs of different sizes. Atomic force microscopy and scanning electron microscopy reveal the successful deposition and homogeneous surface morphology of QD-AlPO4 glass films. Furthermore, as a result of adsorption and confinement from pores of AlPO4 substrate, the photostability of QD-AlPO4 glass films is dramatically improved. The red-shift of QD photoluminescence spectra after depositing onto the matrix and the energy transfer between QDs of different sizes indicate the formation of close-packed QD solid systems. This work extends the research in QD close-packed systems and has important implications for the applications of blended QDs in broadly tunable optical devices and telecommunication.