Computer monitors do not work like that. They emit a mix of 3 fixed spectra. You cannot shift the red to an even longer wavelength. At least not without adding

Computer monitors do not work like that. They emit a mix of 3 fixed spectra. You cannot shift the red to an even longer wavelength. At least not without adding some physical filters on top that only let through the long tail (which is fairly inefficient). At that point you might as well buy specialized LEDs.