Highly luminescent copper-doped ultrathin CdSe nanoplatelets for white-light generation

In this work, the potential of ultrathin pure and copper-doped CdSe nanoplatelets (NPLs) for white-light generation is studied. It is shown that thin populations of CdSe NPLs synthesized at relatively low growth temperatures generate white-light due to combining the band-edge and broad trap-assisted emissions. It is found that the luminescence and photometric properties of the CdSe NPLs can be tailored in a wide range simply by changing their growth temperature. As-grown CdSe NPLs generate white light with a color rendering index (CRI) as high as 75 and color coordinates of (0.31, 0.33) at a correlated color temperature (CCT) of 6438K. Further, to avoid the well-known re-absorption problem and increase photoluminescence quantum yield (PL QY), the thinnest population of CdSe NPLs is doped with copper. It is demonstrated that by copper-doping, the band-edge emission of ultrathin CdSe NPLs can be fully suppressed. Copper-induced emission covers a wavelength range of 400-700nm with PL QY reaching values up to 95%. By integrating the undoped and copper-doped ultrathin CdSe NPLs whith a UV chip, light-emitting devices (LED) emitting within the white-light region of the CIE 1931 chromaticity diagram are fabricated.