While all the phototrophs that are able to split water and produce free oxygen use chlorophyll a, which absorbs only red light and violet light, resulting in a blue-green color, which can be seen as such in some lichens and cyanobacteria, most of them have some accessory pigments, which absorb other parts of the solar spectrum, and then transfer the energy to chlorophyll a.
The green algae, which live only in shallow waters, and the terrestrial plants use as accessory pigment only chlorophyll b, which absorbs a different band of red light than chlorophyll a and also blue light, resulting in a green color.
This is enough for green algae and land plants, because where they live there is abundant light. For land plants the problem is that they have too much light, not too little, with the exception of those which grow under the shadow of trees.
On the other hand, most marine algae use accessory pigments that absorb much more of the solar spectrum, so that the color of chlorophyll is no longer visible and they have overall colors like red, yellow or brown, even very dark brown. This enables such algae to live down to greater depths in the water, where there is less solar light.
So there are a lot of living beings that make very efficient use of light.
Moreover, under water there are many places where practically all light is captured, by multiple layers of algae and bacteria, each layer absorbing some part of the solar spectrum. Even the near infrared light is absorbed by a bottom layer of bacteria, which do not produce oxygen, because the energy of infrared photons is insufficient to split water.
technically the energy in green is also not enough to split water, which (IIRC) is why PSII must ping pong the photon through multiple collector complexes to achieve an electron with enough energy to crack water.
The energy required to split water is around 1.25 eV, while the energy of red photons is already around 1.5 V and the energy of green photons is well above 2 eV.
However, it is true that plants need 2 red photons (or of higher energy), not 1, to generate both free oxygen and a reduced organic substance, NADPH, which is used later to reduce carbon dioxide into carbohydrates. The reason is that the captured solar energy is used not only for these redox reactions, but also for pumping ions across the chloroplast membrane. The energy stored in the ion gradient will be used later to power the chemical syntheses, which need both a reducing agent and additional energy.
The ping-pong is done with electrons, not with photons. There are 2 photosystems, which absorb separately photons, using their energy to transport electrons against the potential gradient. The electrons pass through both photosystems in series, achieving a potential difference between the endpoints that is greater than what is required for splitting water.
The potential difference over each photosystem is significantly smaller than corresponding to the energy of the absorbed photon, because only a fraction of the energy is used for electron transport against a potential gradient, while the rest is used for ion transport against a ion concentration gradient.
Photosystem II contains manganese ions that are oxidized so strongly that they can oxidize the oxygen from water, converting it into free dioxygen. Photosystem I is able to make a strong reducing agent, to which the hydrogen remaining from water is bound.
The green algae, which live only in shallow waters, and the terrestrial plants use as accessory pigment only chlorophyll b, which absorbs a different band of red light than chlorophyll a and also blue light, resulting in a green color.
This is enough for green algae and land plants, because where they live there is abundant light. For land plants the problem is that they have too much light, not too little, with the exception of those which grow under the shadow of trees.
On the other hand, most marine algae use accessory pigments that absorb much more of the solar spectrum, so that the color of chlorophyll is no longer visible and they have overall colors like red, yellow or brown, even very dark brown. This enables such algae to live down to greater depths in the water, where there is less solar light.
So there are a lot of living beings that make very efficient use of light.
Moreover, under water there are many places where practically all light is captured, by multiple layers of algae and bacteria, each layer absorbing some part of the solar spectrum. Even the near infrared light is absorbed by a bottom layer of bacteria, which do not produce oxygen, because the energy of infrared photons is insufficient to split water.