Wavelength conversion element and backlight module

A backlight module, comprising:

• a light source adapted to provide an excitation beam;
• and
• a wavelength conversion element disposed on a transmission path of the excitation beam, and comprises:
• a substrate;
• a blocking wall structure layer disposed on a surface of the substrate and defining a plurality of microgrooves, wherein reflectivity of the blocking wall structure layer is in a range of 1% to 90%;
• and
• a wavelength conversion layer disposed in the microgrooves, wherein the wavelength conversion layer comprises a plurality of wavelength conversion particles, a height of the blocking wall structure layer along a normal direction of the surface of the substrate is greater than a height of the wavelength conversion layer along the normal direction of the surface of the substrate,
• wherein the blocking wall structure layer comprises a plurality of blocking walls with the same extension direction arranged at intervals along at least one direction, and heights of adjacent blocking walls of the plurality of blocking walls are different.