Non-linear light emission of inorganic protonic diodes, H+LEDs

Abstract

Protons behave like electrons. This similarity leads to the concept of proton semiconductors, where water is treated as an intrinsic semiconductor. Water doped with acid becomes a protonic analog of an n-type semiconductor (with excess protons), while water doped with a base is an analog of a p-type semiconductor (excess of hydroxyl groups, “holes”). By combining these two materials, it is possible to create a proton p–n junction and finally even a light-emitting diode (H⁺LED) in which protons are the main charge carriers. This was first observed in our laboratory using a polymer stabilized device. The remaining problem to be investigated was the role of the electron current and the possible effect of polymer instability on light emission. Here we describe a device in which the mechanical stability is maintained by the use of (wet) SiO₂ silica gel doped on one side with H₂SO₄ (proton donor) and SiO₂ doped with Na₂SiO₃ (sodium silicate, water glass) on the other (proton acceptor)) or wet SiO₂ (proton donor) and Al₂O₃ aluminum oxide (proton acceptor). All materials used are insulating to the flow of electrons and thermally stable. In the case of inorganic diodes H⁺LED, emission is extremely intense with non-linear optical effects – collimated light beams and forced Raman scattering (SRS), and the spectrum is blue shifted compared to the emission of polymer-stabilized diodes.