This invention discloses a solution-based synthesis of cesium tin tri-iodide (CsSnI3) film. More specifically, the invention is directed to a solution-based spray-coating synthesis of cesium tin tri-iodide (CsSnI3) thin films. This invention is also directed to effective and inexpensive methods to synthesize the thin CsSnI3 films on large-area substrates such as glass, ceramics, glass, ceramic, silicon, and metal foils. CsSnI3 films are ideally suited for a wide range of applications such as light emitting and photovoltaic devices.