Walker has worked with Petra Cameron to investigate perovskite solar cells, hybrid devices that contain organic and inorganic materials. The active layers of these devices contain perovskite crystal structures, which strongly absorb solar radiation. Electrons within the perovskite are excited across the material bandgap, creating mobile charge carriers that migrate to electron and hole transport layers. Walker was made coordinator of the Horizon 2020 program making perovskite truly exploitable (Maestro). Walker has created protein simulations to understand the structure and function of biologically-relevant molecules.