As global temperatures rise and energy demands increase, the need for clean, renewable
energy sources is more critical than ever. Solar energy is one of the key solutions, with the
majority of solar panels currently on the market being made from crystalline silicon. However, emerging photovoltaic (PV) technologies such as perovskite solar cells have already demonstrated efficiencies comparable to those of silicon solar cells, making them a promising contender to achieve even higher efficiencies.

Most of the layers in perovskite solar cells are deposited via spincoating, which is a fast and easy process but can only be done on laboratory-scale. However, deposition through thermal evaporation offers significant advantages, enabling fabrication of nanometer-thin films and facilitating large-scale fabrication needed for future industrialization of perovskite solar cell. Therefore, this research aims to develop perovskite solar cells entirely through thermal evaporation.

The reported number of hole transport materials deposited through thermal evaporation is limited. Recently, fully thermally evaporated perovskite solar cells have been created using the hole transport materials MoOx and TaTm, and these hole transport materials will be studies in this thesis.

The MoOx and TaTm were used as single and double hole transport layer to replace the
reference layer of spincoated PTAA. It was found that the MoOx in direct contact with the pervovskite resulted in a chemical reaction, which negatively affected the energy alignment. The MoOx also showed poor charge carrier selectivity, resulting in high interfacial recombination. Great hole extraction from the perovskite was observed for TaTm, however, a misalignment of the band energy with the electrode hindered the hole collection. Improved hole transfer was found with MoOx and TaTm being used a double hole transport layer. Here, the TaTm functions as a passivation layer between the MoOx and perovskite, while effectively blocking the electrons. In turn, the MoOx improved the energy alignment from the TaTm to the electrode to improve the hole collection.

A thickness optimization of the hole transport layers was also performed. For MoOx as
single hole transport layer, it was found that number of oxygen vacancies decreased with
thickness, leading to less recombination. No change was observed for TaTm as single hole
transport layer when varying the thickness. However, as a double hole transport layer with MoOx, increasing the thickness of TaTm led to an increase in Voc . Ultimately, a thin layer of 2 nm MoOx with a 5-nm thick TaTm showed the most promising results, demonstrating a final efficiency of 4.73%.
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Many drugs cannot be made without homogeneous catalysis. To increase the yield of drug synthesis, the search for new catalysts continues. Computational catalysis is becoming a more prominent tool since it en- ables to screen many catalysts without performing (m)any laboratory experiments. In this research a com- putational workflow has been created to calculate both electronic (e.g. dipole, ionisation potential, nucle- ophilicity, etc.) and steric (bite angle, buried volume, cone angle, etc.) molecular descriptors. The structures were automatically created starting from the metal centre, some bidentate phosphorus ligands, auxiliary lig- ands, and the substrate. An in-house computational workflow, MACE, is used for for high-throughput gen- eration of structures from the starting bidentate phosphorus ligands, by generating stereo-isomers around to metal centre. Afterwards small substituents (H, CH3, Ph, etc.) are changed by ChemSpaX increasing the number of structures combinatorically. To reduce the computational cost of this workflow, it has been re- searched whether properties of the octahedral geometry could be predicted using properties from a simple model structure containing only the metal centre and the bidentate phosphorus ligand. This model structure did not show a correlation except for the electronic energy and the solvent accessible surface area, which are both primarily influenced by the number of electrons. Other correlations may be found if some other descriptors were calculated which where excluded now, like the HOMO-LUMO gap and the substrate bind- ing energy. The workflow could be extended to machine learning and improved by including symmetry and optical isomerism. ... Read more

Transparent conductive oxides (TCOs) play important roles in information and energy technologies. In the photovoltaic (PV) community, they are normally required to provide sufficient lateral carrier transport towards metal electrodes at the illumination side. Thus, a trade­off between optical and electrical
properties is of critical importance in relevant device fabrications. So far, within the PVMD group, the investigation on TCOs has been mainly focused from an experimental perspective. In this thesis, a firstprinciples approach based on DFT software is investigated to obtain the self­consistent opto­-electrical properties of TCOs.

A comprehensive study is carried out to understand the fundamentals of DFT software, as this is crucial to get reliable results from it. Within the PVMD group, the DFT method is applied on the indium­oxide (IO) host material. It was found that referable results for the (partial) density of states and band
structure could be obtained for this structure using the PBE exchange­correlation (XC) functional. The dielectric function could be obtained by combining the PBE and HSE06 XC functional through the PHSmethod.

Based on a preliminary validation of IO, two case studies are carried out. In these case studies, it is investigated if DFT can be used to compare the opto­-electrical properties of different doping types and ratios. This is done for post­transition metals (Sn), transition metals (W and Mo) and anionic doping
(F). By observing the partial density of states of each element, it was found that significant hybridization of dopant states with the CBM of the IO host states occurs for the cases of Sn­ and F­doping.
Such disturbance in the host conduction band may lead to detrimental influences to the opto­-electrical properties of corresponding TCOs. However, in the cases of W­ and Mo­doped TCOs at commonly used doping concentrations, no hybridization between dopant states and the host conduction band was observed. Furthermore, physical parameters of different TCOs at different doping levels are extracted and compared, such as band gap, effective electron mass, work function and dielectric functions. These results may provide supportive and indicative information for the experimental work.

This thesis work has successfully introduced DFT calculation into TCO investigations within our research group. Although the preliminary results were not sufficiently accurate to predict the opto­-electrical properties of the TCOs in a quantitative way, the qualitative trend can still be used as guidance and support for explaining experimental results. However, many challenges still remain, especially for determining some optical properties like the band gap and dielectric function. Further research is still needed to improve the proposed method. ... Read more