Korean chemists have developed a simple method to make plasma displays by spin-depositing layers of inorganic phosphor onto glass. 

Lanthanide orthophosphates (LaPO₄) nanoparticles doped with cerium or terbium are well known for their intense green luminescence and have already found uses in various optical and labelling applications. However, the application of these phosphors in plasma displays has been limited owing to their tendency to exhibit substantial light scattering that limits the transparency of the films, as well as difficulties in film synthesis and stability. 

Heesun Yang from Hongik University, Seoul, and colleagues made high quality LaPO₄:Ce,Tb nanophosphors using lanthanide nitrates and phosphoric acid along with citric acid and polyvinylpyrrolidone. After spin-depositing several layers of the phosphor onto glass, they found them to be very stable with negligible light scattering loss making them ideal for constructing highly efficient green emitting plasma display panels (PDPs). 'Unlike other conventional nanophosphor studies that typically focussed on their synthesis and characterization, our work provides the feasibility of transparent PDP device fabrication using nanophosphors,' comments Yang. 

Gautam Gundiah, an expert in inorganic phosphors and their applications from the Lawrence Berkeley National Laboratory, Berkeley, US, agrees, 'obtaining a transparent phosphor layer is key to the development of transparent plasma display panels (PDPs),' he says. 'While there have been reports on the fabrication of transparent PDPs by deposition of thin-film phosphors, this study demonstrates an elegant and scalable route to deposit nanophosphor layers and obtain mini PDPs with high quantum yield and excellent transparency despite multiple coatings.' 

The team are not stopping with green nanophosphors, as well as developing phosphors with better quantum yields, nanophosphors that emit other colours are the next target according to Yang. 

Catherine Bacon 

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