Luminescent concentrator design for displays with high ambient contrast and efficiency

Abstract

A key display characteristic is its efficiency (emitted light power divided by input power). Although display efficiencies are being improved through emissive (for example, quantum dot and organic light-emitting) display designs, which remove the highly inefficient colour filters found in traditional liquid crystal displays, polarization filters, which block about 50% light, remain necessary to inhibit ambient light reflection. We introduce a luminescent concentrator design to replace both colour and polarization filters. Narrow-band, large-Stokes-shift, CdSe/CdS quantum dot emitters are embedded in a luminescent concentrator pixel element with a small top aperture. The remainder of the top surface is coated black, reducing ambient light reflection. A single pixel demonstrates an extraction efficiency of 40.9% from a pixel with an aperture opening of 11.0%. A simple proof-of-concept multipixel array is demonstrated. Inefficient filters and overall efficiency are issues for display technology. Luminescent concentrator pixels have been used with CdSe/CdS quantum dot emitters, which enable both colour and polarization filtering, as well as nearly 41% extraction efficiency.