Daylight was developed by Peter at Greg's behest. Peter believed that Greg would use it to safely expose the Umbrella Corporation's experiments to the public, but in reality, Greg was planning to use it as leverage against Umbrella.
Peter created a simple recipe for the vaccine: V-Poison (from mutated wasps), T-Blood (from a creature infected by the T-virus), and finally, P-Base (a chemical compound requiring careful storage and mixing). When placed in a special incubator, the vaccine will be generated automatically. The Daylight is shown as a bright white liquid, when it is fully prepared.
Always poetically minded, Peter named the vaccine "Daylight," because there is "No need for an Umbrella in the Daylight."
At some point prior to the leaking of the T- virus into Raccoon City, Peter learned of Greg's true motives. Although he got a message to his long time friend, George Hamilton, by the time the doctor could get to the University, Peter was found dead from a gunshot wound in his office.
Although dead, Peter still aided his old friend and his companions in the form of research notes scattered throughout the facility. Their survival hinged upon obtaining Daylight, becoming cured of the virus, and escaping the doomed city before it was wiped out by a missile strike.