Semiconducting Pilymer Full Device Modelling And Simultion Based On The Theory Of Charge Transport In Disordered Matter

Conjugated polymer materials with the merits of light weight, cheap, convenient fabrication, have brilliant prospect in application. Comparing with inorganic semiconducting materials, organic semiconducting materials show poor charge transport ability,to be specific, the mobility is still too low. To date, the devices using polymer materials are still at an early stage of commercialization.In this thesis, we will show how to develop full device models of organic/polymer solar cells and organic field-effect transistors by adopting mesoscopic Pauli master equation method with disorder matter system charge transport theories and proper descriptions of exciton diffusion, charge carriers recombination, metal-semiconductor contact condition, etc. Full device model simulation skills make it possible to connect microscopic physics process with macroscopic device performance, which is helpful for understanding the origins of limitations and provide directions of further improvement. Comparing with other full device models, to be specific, the dynamic Monte Carlo models which also include many phenomenological parameters, our model is more efficient.For the polymer bulk heterojunction(BHJ) solar cells, photogenerated exciton diffusion and separation, free charge carriers transport and recombination are key steps.In the stage of polymer BHJ solar cells full device model testing, we found that: There exists non-Arrhenius correlation of mobility and energy disorder; By introducing annealing simulation, it’s found that there exists an optimum morphology which is the result of trade-off between exciton separation surfaces and charge transport channels;The relation between mobility and cell performance is still a controversial issue. We found that with the increase of mobility, device efficiency will increase gradually and finally level off; It’s also found that local charge accumulation caused by unbalance of electron and hole mobilities or the electrode contact barrier heights at both electrodes can lead to significant efficiency loss. The origin of such loss is due to enhanced charge carrier recombination.For the purpose of properly dealing with charge injection from the electrode and extraction into the electrode, we introduced phenomenological parameters about contact conditions, as a result the injected dark current and extracted photocurrent can be simulated and fitted with experimental data. It’s found that optimized level tuning can significantly improve the device efficiency; And the origin of higher contact barriers resulting in reduced internal quantum efficiency is the enhanced bimolecular recombination rate caused by local space charge accumulation; In addition, the correlation between contact barrier height and bimolecular recombination rate is robust, but it gets less stronger when extended to geminate recombination rate. In the work of studying the mechanism of polymer ferroelectric material as the interfacial layer in polymer BHJ solar cells, we argue that the electrode improvement and energy level alignment mechanism is reasonable, whereas the mechanism of polarized layer introducing both permanent additional internal electric field and series resistance is not that complete.Organic field effect transistors are injection-type charge transfer device which have three electrodes. The full device model of organic field effect transistors can be regarded as a simplified version of our already built solar cells model. For now, the application of this model includes simulating the output characteristics, the charge carrier distribution along the device thickness direction, the correlation between energy disorder and mobility, etc, while the corresponding results are proved to be credible.