Answer: B. Electroluminescence.
Answer analysis: We first need to understand the basic working principle of LED lamps (light-emitting diodes) and compare the luminescence principles represented by each option.
A. Thermal radiation: Thermal radiation is the phenomenon that an object radiates electromagnetic waves due to its temperature. This radiation is related to the temperature of the object, but the light emission of LED lamps does not generate light radiation by heating the object, so this option is incorrect.
B. Electroluminescence: Electroluminescence refers to the phenomenon that the electrons excited by the electric field generate an electric field by applying a voltage across the two ends of the material, and the electrons excited by the electric field recombined with holes to release energy and emit photons. This is exactly the working principle of LED lamps. When the current passes through the semiconductor material in the LED lamp, the electrons and holes recombined, releasing energy and emitting in the form of photons, thereby generating visible light.
C. Photoluminescence: Photoluminescence refers to the phenomenon that an object absorbs light energy and excites photons under the irradiation of light. This is usually used for fluorescent materials or lasers, etc., rather than the working principle of LED lamps.
D. Chemiluminescence: Chemiluminescence refers to the phenomenon that the energy released by chemical reactions directly excites light radiation. This type of luminescence is usually related to chemical reactions, such as bioluminescence, chemiluminescence analysis, etc., which is inconsistent with the luminescence principle of LED lamps.
In summary, the luminescence principle of LED lamps is electroluminescence, that is, the electrons and holes in the semiconductor material are stimulated by current to recombine, release energy and emit light in the form of photons.
Therefore, the correct answer is B. Electroluminescence.