This document discusses the fabrication of organic bulk heterojunction solar cells. It begins with an introduction to organic solar cells and their advantages. It then describes the working principles of organic polymer solar cells including light absorption, exciton diffusion, charge transfer, and charge collection. The common layer stack is explained including the active layer, transport layers, electrodes, and substrates. Fabrication methods like spin coating and spray coating are outlined along with specific fabrication steps for layers. Performance parameters like open circuit voltage and power conversion efficiency are discussed. The effects of UV irradiation treatment and adding zinc oxide nanoparticles are evaluated.