Printing of electronics has been gaining a lot of attention over the past decade as a low cost alternative to conventional electronic fabrication methods. A significant development in this area was the possibility to print a silicon precursor, polydihydrosilane, which can directly be transformed into polycrystalline silicon by an excimer laser treatment. Due to the limited laser heat diffusion, low-cost flexible substrates such as plastics and even paper could be used that typically have low thermal budgets. Since the silicon precursor is sensitive to ultraviolet light and may.transform in a photochemical reaction, the question arises whether the excimer laser crystallization is predominantly photochemical or rather a thermal reaction. In this work, a model is developed and reflected to experimental data, to understand the physics behind the process. Through finite-element analysis and experimental characterizations it was observed that the physics behind the process was predominantly thermal, and that instead of an intermediate transition to a-Si, a direct transformation to poly-Si exists. By understanding this process, the treatment can be optimized or more efficient tools can be used that would enable a low cost production of high performing silicon devices. (C) 2017 Elsevier B.V. All rights reserved.