Zinc phosphide (Zn3P2) constitutes as a promising solar absorber material due to its high absorption and carrier moblity as well as due to the abundance of zinc and phosphorous in the earth crust. Since the first published studies few decades ago, the efficiencies of Zn3P2-based solar cells have remained below its potential. We believe this is mostly due to the limited understanding of how to tune its optoelectronic properties. In this talk we report on the progress towards the understanding of the growth and functional properties of the material such as light absorption, carrier concentration and mobility [1-5]. We report selective area growth as the method that results into the highest quality material as well as with the highest conversion efficiency, beyond the previous published record ~6%. We finalize by providing the main design rules for next-generation Zn3P2-based heterojunction solar cells, which should allow us to go beyond the current conversion values.