 The color tunability of an organic light emitting diode, OLED, depends on the thickness of the thallocyanine, H2PC, layer. Thinner layers result in cooler colors while thicker layers produce warmer colors. Additionally, the H2PC layer acts as a barrier to prevent electron transfer to the ALK3 layer, resulting in white color emission with temperature tunability. This article was authored by Tejunan, Bum Ho Choi, J-Wing Yu, and others.