I have a master's degree in clinical psychology and wrote many articles on positive psychology. I am looking for a position at the university for a Ph.D.
Of course the University of Pennsylvania is the headquarters for Positive Psychology. If you want to pursue a related topic, that you could probably work on in any Psychology program, you could look at how giving promotes dopamine, oxytocin, and serotonin levels. There's a reference on the bottom of this response.
Before I knew about this research, I had an unsatisfying experience with buying gifts for kids, especially when I heard that parents sometimes sold the gifts for cash and the kids received nothing. I started handing out $20 to five people at Christmas who could use a boost. Then I wrote two books, A Pocketful of $20s and Three Worries, in which the protagonist shares many ways to brighten someone’s day with a $20 gift at Christmas. Also included are ways to make the receiver feel recognized and valued and never less than.
Here's one story. On our way back from a long trip, we pulled into McDonalds. The woman at the window was particularly nice. I gave her a $20 and told her to keep the change from the bill. She was flustered and not sure what to do with the money. I told her to put the change in her pocket. She leaned closer to the window and told me her children were too young to do anything for her on this Mother’s Day so the $12.75 change would be her Mother’s Day present.
This topic could certainly use more research and is a developing field.
Dunn, E. W., Aknin, L. B. & Norton, M. I. Spending money on others promotes happiness. Science 319, 1687–1688 (2008).
There is the Master of Applied Positive Psychology (MAPP) program at UPenn. Dr. Martin Seligman helped to develop that program (I believe he may still be teacher there...) and worked on research related to the topic alongside Csikszentmihalyi.