| Description |
Metal oxide semiconductors have a vast array of applications in electronic devices such as transistors, photovoltaics, LEDs, and sensors. There are many methods utilized by researchers and industry to deposit these materials (mainly variations of solution or vapor processing) into thin films. By understanding the effects of processing conditions on metal oxide properties such as crystallinity, mobility and refractive index, metal oxides can be controlled and tuned to better suit a specific application. Further, the ability to reliably control negative effects of processing, such as oxygen vacancy defects in solar cell materials and poor energy level alignment, is very valuable in terms of device stability and reproducibility. One of the most important uses of thin-film metal oxides is as transport layers in solar cells, where mobility, defects, and energy level alignment are of utmost importance. The importance of these transport layers is so pronounced that they can control the growth and stability of the active perovskite material, deposited atop the transport layer. Perovskites based on methylammonium lead halides, CH3NH3PbX3 (X = Cl-, Br-, I-) have emerged as one of the most promising materials in solar cell technology, demonstrating efficiencies as high as 22.1 % and cementing the idea of utilizing them to replace silicon solar cell technologies. Although the photovoltaics field has witnessed a significant progress in the power conversion efficiency (PCE) of perovskite solar cells, unveiling the contribution of the various factors (i.e., energy level alignment, trap states, electron (hole) mobility, interface interactions, and morphology) affecting the observed PCEs is extremely crucial to achieve reproducible and stable devices. In addition, the poor stability toward moisture, ultraviolet irradiation, heat, and bias voltage of the perovskite layer and its various device interfaces is severely limiting its outdoor operation and commercial feasibility. This work aims to understand charge transport and recombination within conventional perovskite solar cells due to modifications of the morphology, optoelectronic properties, and energy levels of the titania electron transport layer via processing conditions. We also investigate the efficacy of perovskite crystal crosslinking via alkyl and aromatic boronic acid ammonium molecules under continuous ultraviolet irradiation. |
