Memristives Schaltverhalten in selbst-assemblierten Nanopartikel-Systemen

In this work, the self-assembly of functional nanoparticle composites towards integration into future three-dimensional electronic circuitry was investigated. Using complementary surface-functionalization of metal and semiconductor nanoparticles, self-assembly of heterogeneous nanoparticle agglomerates in dispersion and the formation of nanoparticle arrays on oxide surfaces was shown. Electrical characterization of these systems yielded pronounced non-volatile bipolar memristive switching and threshold switching behavior, respectively.In dieser Arbeit wurde die Selbstassemblierung funktionaler Nanopartikelsysteme in Richtung der Integration in zukünftig dreidimensionale elektronische Schaltkreise untersucht. Durch komplementäre Oberflächenfunktionalisierung von Metall- und Halbleiternanopartikeln wurde die Selbstassemblierung von heterogenen Nanopartikel-Agglomeraten in Lösung und die regelmäßige Anordnung von Nanopartikeln auf Oxidoberflächen gezeigt. Die elektrische Charakterisierung dieser Systeme zeigte jeweils ausgeprägtes nicht-volatiles, bipolares memristives Schaltverhalten und Schwellspannungs-Schaltverhalten

Uso do método Monte Carlo cinético no estudo do transporte de carga em heterojunções orgânicas livres de fulerenos

Dissertação (mestrado)–Universidade de Brasília, Faculdade UnB de Planaltina, Programa de Pós-Graduação em Ciência de Materiais, 2020.A compreensão do transporte de carga em dispositivos fotovoltaicos orgânicos de heterojunção em massa (BHJ) tem sido largamente impulsionada no últimos anos pelas modelagens obtidas via simulações de Monte Carlo cinético (kMC). Esta técnica constitui uma forma potencialmente mais poderosa e versátil de se obter informações precisas a respeito dos mecanismos de transporte, pois ela permite representar a morfologia complexa das misturas de BHJ e rastrear o comportamento dinâmico de partículas individuais. Neste trabalho, o transporte eletrônico em células solares orgânicas (OSC) é teoricamente estudado na estrutura de um modelo baseado no algoritmo kMC, onde as teorias de Marcus e Miller-Abrahams são implementadas para modelar a taxa de transferência de carga. As simulações foram feitas com o auxílio dos programas de código aberto Excimontec.exe e Ising_OPV.exe, tendo como foco estudar a mobilidade dos portadores de cargas nas heterojunções compostas por unidades aceitadoras livres de fulereno BYG-1/SMD e BYG-2/SMD (materiais manipulados numa escala molecular usando a unidade de fluoreno doador de elétrons como o núcleo central, conectado em ambos os lados ao grupo 2-etilhexil naftamida que retira elétrons através dos grupos ligantes formado por fortes aceitadores de elétrons 5-fluorobenzo[c][1,2,5]tiadiazole e benzo[c]-[1,2,5]tiadiazole) juntamente com um doador de pequenas moléculas (SMD) apropriado.The understanding of charge transport in mass heterojunction (BHJ) organic photo- voltaic devices has been largely driven in recent years by modeling got via kinetic Monte Carlo (kMC) simulations. This technique is a potentially more powerful and versatile way to get accurate information about the transport mechanisms, as it allows us to represent the complex morphology of BHJ mixtures and to track the dynamic behavior of individual particles. In this work, electronic transport in organic solar cells (OSC) is theoretically studied in the structure of a model based on the kMC algorithm, where the theories of Marcus and Miller-Abrahams are implemented to model the load transfer rate. The simulations were made to with the help of the open-source programs Excimontec.exe and Ising_OPV.exe, focusing on studying the mobility of charge car- riers in heterojunctions composed of fullerene free accepting units BYG-1/SMD and BYG-2/SMD (materials manipulated on a molecular scale using the electron donor flu- orene unit as the central core, connected on both sides to the 2-ethylhexyl naphthamide group that removes electrons through the binding groups formed by strong electron acceptors 5-fluorobenzo[c][1,2,5]thiadiazole and benzo[c]-[1,2,5]thiadiazole) together with an appropriate small molecule donor (SMD)

Generalized Kinetic Monte Carlo Framework for Organic Electronics

In this paper, we present our generalized kinetic Monte Carlo (kMC) framework for the simulation of organic semiconductors and electronic devices such as solar cells (OSCs) and light-emitting diodes (OLEDs). Our model generalizes the geometrical representation of the multifaceted properties of the organic material by the use of a non-cubic, generalized Voronoi tessellation and a model that connects sites to polymer chains. Herewith, we obtain a realistic model for both amorphous and crystalline domains of small molecules and polymers. Furthermore, we generalize the excitonic processes and include triplet exciton dynamics, which allows an enhanced investigation of OSCs and OLEDs. We outline the developed methods of our generalized kMC framework and give two exemplary studies of electrical and optical properties inside an organic semiconductor