Current photoelectrochemical devices for water electrolysis suffer from low stability and efficiency. Aims to address both those needs have been realized using a system that uses two sequential solar light absorbers (semiconductors) — in conjunction with oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) catalysts. Each absorber has a built-in electric field (band-bending) achieved by doping to allow matching of valence (VB) and conduction (CB) band energy levels to the electrochemically required OER and HER potentials. To improve charge separation efficiency and lifetime, methods for creation of thin films of OER (LiCoO₂) and HER (Ni-P) catalysts have been developed. The OER catalyst is coupled to a mid bandgap light absorber (~1.7-2.5 eV), while the photocathode is comprised of the Ni-P on p-Si (100). During device fabrication, interfacial effects and surface morphologies for each electrode were analyzed by x-ray photoelectron spectroscopy, atomic force microscopy, helium ion microscopy, x-ray diffraction, and Rutherford backscattering. Photoelectrochemical measurements inclusive of faradaic efficiency and IPCE for each electrode individually as well as a single overall water splitting device have been measured. Various device architectures are considered and discussed to achieve the most cost-effective PEC design.