A method of forming a multicolour light emitting array, the method comprising: providing a first light emitting device configured to emit light with a first primary peak wavelength, a second light emitting device configured to emit light with the first primary peak wavelength and third light emitting device configured to emit light with the first primary peak wavelength; forming a colour conversion region on the first, second and third light emitting devices, wherein the colour conversion region is configured to absorb light with the first primary peak wavelength and emit light with a second primary peak wavelength longer than the first primary peak wavelength; masking a portion of the colour conversion region on the third light emitting device and photo-bleaching a portion of the colour conversion region on the first light emitting device and the second light emitting device such that the colour conversion region on the first light emitting device and the second light emitting device is at least partially transparent to light with the first primary peak wavelength; subsequently forming a further colour conversion region on the colour conversion region, wherein the further colour conversion region is at least partially transparent to light with the second primary peak wavelength, and configured to absorb light with the first primary peak wavelength and emit light with a third primary peak wavelength longer than the first primary peak wavelength and shorter than the second primary peak wavelength; masking a portion of the further colour conversion region on the portion of the colour conversion region on the second light emitting device and the third light emitting device and photo-bleaching a portion of the further colour conversion region on the portion of the colour conversion region on the first light emitting device such that the further colour conversion region on the portion of the colour conversion region on the first light emitting device is transparent to light with the first primary peak wavelength, thereby to enable light with the first primary peak wavelength to be emitted by a first pixel associated with the first light emitting device, light with the third primary peak wavelength to be emitted by a second pixel associated with the second light emitting device and light with the second primary peak wavelength to be emitted by a third pixel associated with the third light emitting device. providing a first light emitting device configured to emit light with a first primary peak wavelength, a second light emitting device configured to emit light with the first primary peak wavelength and third light emitting device configured to emit light with the first primary peak wavelength; forming a colour conversion region on the first, second and third light emitting devices, wherein the colour conversion region is configured to absorb light with the first primary peak wavelength and emit light with a second primary peak wavelength longer than the first primary peak wavelength; masking a portion of the colour conversion region on the third light emitting device and photo-bleaching a portion of the colour conversion region on the first light emitting device and the second light emitting device such that the colour conversion region on the first light emitting device and the second light emitting device is at least partially transparent to light with the first primary peak wavelength; subsequently forming a further colour conversion region on the colour conversion region, wherein the further colour conversion region is at least partially transparent to light with the second primary peak wavelength, and configured to absorb light with the first primary peak wavelength and emit light with a third primary peak wavelength longer than the first primary peak wavelength and shorter than the second primary peak wavelength; masking a portion of the further colour conversion region on the portion of the colour conversion region on the second light emitting device and the third light emitting device and photo-bleaching a portion of the further colour conversion region on the portion of the colour conversion region on the first light emitting device such that the further colour conversion region on the portion of the colour conversion region on the first light emitting device is transparent to light with the first primary peak wavelength, thereby to enable light with the first primary peak wavelength to be emitted by a first pixel associated with the first light emitting device, light with the third primary peak wavelength to be emitted by a second pixel associated with the second light emitting device and light with the second primary peak wavelength to be emitted by a third pixel associated with the third light emitting device.