I can’t come up with a good answer for this…
It neither supported or denied it, it proved that light traveled as a particle and a wave. By a particle I mean it is a wave packet, in small intensities light travels as a particle but in large intensities it travels like streams of waves.
The photoelectric effect showed that light was capable of produced electricity but ejecting electrons from metal which in turn generates electric potential energy, voltage, and the more photons to eject electrons, the more electrons were ejected. A wave of light carries photons and when it comes in contact with other particles, it acts like a particle. Two seemingly opposing theories of light became one after 1905.
By explaining why frequency, not the brightness, of incident light determined whether electrons would be ejected from some metals. Because higher frequencies mean higher energy, there is a threshold frequency needed to free the electrons. All that brighter light did was increase the number of photons, not their individual energies.
The outcome of the photoelectric effect showed that light is composed of packets of quanta (discrete levels of energy) called photons. These photons act like particles in collisions, and can transfer energy. Now I wouldn’t claim that the photoelectric effect supports the particle theory of light as all subatomic particles have wave-particle duality.