© 2011-2012 IEEE.Achieving low-cost and high-performance solar cells based on heterojunction of metal-oxide-semiconductors with silicon (Si) is a difficult task. We herein report the development of cost-effective and efficient SnO2/p-Si heterojunction-based solar cells using the low-temperature hydrothermal method. The fabrication of SnO2/Si heterojunction-based solar cells is realized with various thicknesses of SnO2 layer deposited by controlling the hydrothermal deposition time. The measurements of scanning electron microscopy, optical spectra, four-point probe conductivity, current-voltage (I-V), and capacitance-voltage (C-V) reveal that the thickness of SnO2 emitter layer significantly influences the electrical properties and the photovoltaic performance of the devices. The best power conversion efficiency of 3.09% (Jsc = 20.28 mA/cm2, Voc = 0.312 V, and FF = 48.84%) is achieved for the solar cell having n-SnO2 thickness of 391 nm. The experimental findings disclose that the efficiency of the cells is extremely dependent on the emitter layer thickness, which plays a vital role in determining light-harvesting characteristics and carrier collective capabilities of the cells.