Advanced modelling of hybrid organic-inorganic devices for optoelectronic applications

In the last decades the use of organic materials for optoelectronic applications has increased strongly. This led to the advent of new technologies especially in photovoltaics and light-emitting devices field. The optoelectronic properties of devices equipped by hybrid organic-inorganic or purely organic semiconductors, they strongly depend on the complex mechanisms which take place as consequence of the molecular disorder or the lattice distortion. For these reasons, the modelling of these mechanisms has become crucial in the simulation field, since to date the numerical simulation plays a relevant role in the design and optimization processes of optoelectronic devices. The traditional drift-diffusion approach typically used for charge transport modelling in inorganic semiconductors exhibits some limitations in taking into account those mechanisms, which take place especially in disordered materials. For this reason we present a generalized multiparticle drift-diffusion model aimed to overcome the limitations imposed by the traditional approach, and capable to take into account of multiple carrier populations, whether charged and neutral, allowing this way to explicitly consider excitons. This simulation tool it was then exploited to study and analyze some of the materials open issues for optoelectronic technologies such as perovskite solar cells and blue organic light emitting diodes. Consequently the work is divided in two separated parts, which have been carried forward in parallel. In the first part we focus our the investigation on the methylammonium lead iodide perovskite open issues, since it represents the leader material employed in perovskite solar cell technology. To do this we perform advanced modelling aimed to reproduce effects such as charge-carrier separation aided by the residual polarization, the potential barriers formation at grain boundaries due to the interfacial trap-mediated recombination processes, and the hysteresis effect of the J-V characteristic caused by the ion motion and accumulation which take place within grains. The second part focuses on the macroscopic simulation of OLEDs, including the exciton transport. Here we analyze two different technologies such as phosphorescence-based OLED and thermally activated delayed fluorescence OLED, both depending on the inter-system crossing mechanism leading to the blue emission.