A phenomenon thermal denaturation of Copper(I) complexes with blue-to-red emission transition for white color displays

Here we report two luminescent copper complexes with different structures and luminescent properties, the blue-green [CuI(dmpyHS) (PPh₃)₂]⸱CH₃CN (CuPy-PPh₃) and the red [Cu₆(dmpyS)₆]⸱H₂O (CuPy). When the blue-green light (CuPy-PPh₃) is heated to above 147 °C, it loses the phosphine-containing ligand, PPh₃, and turns into CuPy and instead emits red light. Many luminescent complexes show the change of luminescence properties when the temperature is lower than room temperature, while the luminescence change of CuPy-PPh₃ occurs during the heating process above room temperature. Even more interesting, the luminescence wavelength transition span is large, from blue-green light emission at 490 nm to red light at 676 nm. The luminescence of the two copper complexes covers the three primary colors of red, green and blue required for the formation of white light emitting diodes WLEDs, which has potential in the development of non-rare earth phosphor white color displays. The integration of CuPy-PPh₃ and CuPy on a 395 nm near-ultraviolet chip can assemble WLEDs with good white light properties, which provides a new way for the construction of rare earth-free phosphor WLEDs. The synthesis of the two luminescent copper complexes is simple and environmentally friendly. Even though the structures of two copper complexes have been reported, the synthesis methods are different from those in the related literature and the luminescence properties of these complexes have never been described previously. The red emission copper complex CuPy is obtained by the thermal conversion of the blue-green emission copper complex CuPy-PPh₃, which is a new phenomenon discovered for the first time in this work.