This report is dedicated to the modelling and understanding of organic devices functionement and more particularly to organic diodes. First, we modelled and analysed I-V caracterisations of planar (diodes) and longitudinal (resistive sticks) devices made with TIPS-pentacene. We could explain the reason of the rectifying behavior of devices based on undoped semiconductor. The dynamic aspect was then analysed with the help of a numerical model which was simplifyed in a semi-analytical one. This allowed us to find parameters who have an impact on the cutoff frequency. Finally, as there is a growing interest on organic photodiodes whose applications are organic photodetectors or solar cells, we modellised, in the last part, the impact of light on the functionnement of organic diodes. We studyed the impact of both electrical parameters and optical ones (thicknesses, mobility, dissociations rate of excitons, optical indexes, etc...) on dark current and under illumination.