The mechanisms of radiative recombination and electroluminescence (EL) in structures based on CsPbBr3 perovskite nanocrystal (NC) films in the matrix of semiconductor polymer MEH-PPV are considered. It has been shown that two mechanisms determine the EL intensity in light emitting field effect transistors (LE-FETs) with active layers based on MEH-PPV: CsPbBr3 (NC) films: recombination of charged carriers injected into the polymer matrix and recombination at the polymer / NC perovskite interface. The results of theoretical and experimental studies have shown that the superlinear dependence of the EL intensity on the level of electrical excitation in LE-FETs based on MEH-PPV: CsPbBr3 (NC) is due to the mechanism of electron tunneling through the potential barrier at the electrode.