The emitted wavelength can be tuned by the choice of Q-dot material and size. Recently, colloidal semiconductor quantum dots (Q-dots) have gained a lot of ground as color conversion materials 15, 16, 17, 18 due to improvements in quantum yield, color purity, and synthesis methods. Pigments and dyes are sensitive to photobleaching and are prone to degradation over time.

In general, these materials absorb light at energies higher than the characteristic energy gaps and emit light at specific wavelengths (colors) due to a fluorescence/luminescence process. Additionally, the use of dyes 12, 13 and wavelength conversion particles/polymers (WCP) 9, 14 are widely reported. Absorption in phosphors like Yag:Ce is however low and thick layers, typically hundreds of microns, are needed to absorb source blue light significantly. Well known is the use of phosphors for wavelength down-conversion in high-brightness blue light emitting diodes (LEDs) to obtain white light illumination (white LEDs) 3, 6, 7, 8. The (tapered) GaInP nanowire arrays, despite very low fill factors (~ 24%), can out-perform the micro-arrays and bulk-like slabs due to a better in- and out-coupling of source and emitted light, respectively.Ĭolor conversion materials are interesting for many applications in the field of optoelectronics, e.g., solid-state lighting 1, 2, 3, 4, 5, 6, 7, 8, displays 2, solar cells 9, biomedicine 10, and optical communication 11. Room-temperature photoluminescence measurements with 405 nm and 532 nm laser excitation are used for proof-of-principle demonstration of color conversion from the embedded GaInP structures. It is shown that (embedded) 1 μm-high GaInP nanowire arrays can be designed to absorb ~ 100% of 450 nm and 532 nm wavelength incident light. Finite-difference time-domain simulations and spectrophotometry measurements are used to design and validate the GaInP structures embedded in (stand-alone) transparent films for maximum light absorption and color conversion from blue (450 nm) and green (532 nm) to red (~ 660 nm) light, respectively. Substrate-free GaInP micro- and nanostructures obtained by selectively etching the GaAs sacrificial layers are then embedded in a transparent film to generate stand-alone color converting films for spectrophotometry and photoluminescence experiments. GaInP nano- and microstructures, fabricated using top-down pattern transfer methods, are derived from epitaxial Ga 0.51In 0.49P/GaAs stacks with pre-determined layer thicknesses. Color conversion by (tapered) nanowire arrays fabricated in GaInP with bandgap emission in the red spectral region are investigated with blue and green source light LEDs in perspective.

Wavelength color converter