For the purpose of my project, I needed an simple instrument that could be controlled and modulate by only one number (as it is the only information I receive from the light sensor). I thus followed this tutorial in order to create a synthesizer.
Each keyboard touch is link to a number between 36 and 83. I will then be able to link the number send by the light sensor to a note. The 5 small graphs that are in the patche are envelopes that modulate the sound in order to make it a little bit more warm and better. They modulate it in different ways that you can select in the drop down menu that is connected to a selector object. In this one, the selector object act as an oscillator.
One more thing that can be adjusted is the domain of the envelopes... the duration in millisecond it takes for the sound to go through the graph.
I believe this basic synthesizer is a good starting point to connect with the photo sensor and use the light to trigger and modulate the sounds in different ways.