Provided are a display panel and a preparation method therefor, and a display device The display panel comprises several pixel units; each pixel unit comprises a red sub-pixel, a green sub-pixel, and a blue sub-pixel; the red sub-pixel, green sub-pixel, and blue sub-pixel each comprise a negative electrode, an electron transport layer, a quantum dot light-emitting layer, a hole functional layer, and a positive electrode which are stacked; the material of the electron transport layer is Mg-doped ZnO nanoparticle; the doping concentration of Mg in the electron transport layer of the red sub-pixel, the doping concentration of Mg in the electron transport layer of the green sub-pixel, and the doping concentration of Mg in the electron transport layer of the blue sub-pixel are sequentially decreased. The display panel can respectively adjust the carrier balance with respect to the different requirements of the red sub-pixel, the green sub-pixel, and the blue sub-pixel, so that finally the red sub-pixel, the green sub-pixel, and the blue sub-pixel can simultaneously achieve the optimal carrier balance, thereby improving the performance of the display panel.