Additives for active layer design & trap passivation in organic photovoltaics
Said, Marcel M.
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This dissertation explores the employment of solid additives in organic photovoltaic devices with the goal of customizing the electronic properties of the semiconducting materials, as well as the morphological effects of their introduction into active layer bulk heterojunctions. The outcomes of additive introduction are characterized primarily by photovoltaic device measurements, photoelectron spectroscopy, scanning probe microscopy, and X-ray diffraction techniques; other methods are implemented in certain projects, and are explained within the respective chapters they are applied. Ternary blend active layers, where a new component is added as a method of additive-based morphological control in an attempt to improve electron transport through non-fullerene acceptor domains, is the focus of Chapter 2. Chapters 3 and 4 involve the use of molecular dopants for trap passivation with common donor homopolymers and heteropolymers, respectively, within the active layer, and probes their ability to be dispersed with the local order of the system. Finally, Chapter 5 describes the introduction of molecular dopants into an amorphous inorganic charge-transport interlayer, with unexpected effects on oxide composition and device performance. Conclusively, these projects involve the incorporation of additives into systems that contained a number of impurities and imperfections previous to their addition, which makes the results, and their interpretation, new territory for organic electronics.