In thin film solar cells there is a front contact layer called TCO, transparent conducting oxide. This layer requires high conductivity and high transmittance. Different materials such as Tin doped indium oxide (ITO) and Aluminum doped zinc oxide (AZO) are current good alternatives but several other materials are investigated to find even better materials. One of them is tungsten doped indium oxide (IOW). This project was about investigating the deposition process for IOW and characterize the properties of IOW thin film to investigate the possibilities for implementing this material as a contact layer in thin film solar cells. The results from the two batches of depositions varied a lot. Some samples came out dark, but some were transparent and had a high transmittance, suitable for a TCO. The highest transmittance reached through this process was around 95 % in the infrared (IR) range and around 90 % in the visible range. When it comes to the resistivity, no IOW-samples reaches desired levels for a TCO. The lowest resistivity reached was 6.36 * 10-4 W cm. The results showed that the sample with the lowest resistivity was the undoped material, which is contradicting the current theory on the subject. The lowest resistivity for the IOW film was 6.50 * 10-3 W cm.

A numerical model have been developed in order to describe and achieve deeper understanding of experimentally obtained I-V curves from Cu2O/ZnO p-n heterojunctions for potential use as future solar cell material. The model was created using the simulation software COMSOL Multiphysics® and their semiconductor module. To experimentally study the samples two approaches were taken: (1) macro-electrical measurements and (2) local I-V measurements using conductive AFM. The final model is one-dimensional, time dependent and with the ability to study photovoltaic effects of samples with different layer thickness at different voltage ramping speeds and different light irradiance. The model is also able to study the effects of using different contact materials by treating the contacts as ideal Schottky contacts. The dynamic behavior of a Cu_2O/ZnO heterojunction was studied by considering the systems response to a voltage step and the effect of changing the voltage ramping speed. The output from the step response, the current as a function of time, is varying a short time after a step has occurred before settling on to a steady value. The response also shows an overshoot of the current in the direction of the voltage step and the final steady value depends on whether the junction is conducting or not. The effects of this behavior on the shape of the I-V curves are witnessed when studying the different voltage ramping speeds. The voltage is ramped from 2 V to -2 V and back again for different speeds (V/s). The I-V curves have different shapes when sweeping the voltage in different directions and the magnitude increases with increasing speed. The photovoltaic effects were studied by applying different light irradiances. The behavior of the model agrees well with the theory for an ideal diode solar cell. An investigation was done of how the work function of the metal in contact with the Cu_2O affects the shape of the I-V curve under dark and illuminated conditions. The metal work function was changed from 4.5 eV to 6.5 eV in steps of 0.4 eV and does not affect the shape of the I-V curves much in dark after increasing it above 4.5 eV. The effects are more visible under illuminated conditions where a "step"-behavior appears for the lower values of the work function. Only one of the physical samples show a noticeable light effect. The macro-electrical measurement on this sample is compared with simulated results and are in qualitative agreement with each other. The agreement between the local electrical measurements and the simulated results is not as good with the current model.

Syftet var primärt att undersöka hur stor degraderingen hos svenska solcellssystem, som varit i drift mellan 3 och 9 år, är. Data över produktion samlades in från 37 anläggningar i Mellansverige och normaliserades för meteorologiska förutsättningar. Det erhölls en årlig försämringstakt av normaliserad produktion på 1,4 % i medeltal. Resultatet ansågs inte vara tillräckligt väl normaliserat och kunde därför inte approximera degraderingstakten. Dessutom fanns för många osäkerheter, framför allt i strålnings- och temperaturdatan, för att resultatet skulle kunna bli trovärdigt. Globalstrålningsdata mätt för varje solcellsanläggning samt paneltemperatur istället för lufttemperatur hade behövts användas. Ett mer trovärdigt resultat skulle dessutom kunna erhållas genom att använda data från fler och äldre anläggningar, där yttre parametrar som exempelvis skuggning, utbyggnad av anläggning och byte av komponenter varit känt. En analys av en mer än 30 år gammal solcellsanläggning utfördes där den visade sig fortfarande producera ungefär lika mycket el som när den installerades. Anläggningen visade därmed på att solceller kan hålla en lång tid i svenska förhållanden. Slutligen undersöktes tillgängligheten av el från solcellssystem genom utskick av formulär till olika solcellsinnehavare. Det visade sig att ingen specifik komponent var överrepresenterad när problem uppstod samt att större och äldre anläggningar i större utsträckning stötte på problem som påverkade deras elproduktion. Tillgängligheten visade sig vara god.

Humanity has great energy demands, and must simultaneously combat climate change by curbing anthropogenic greenhouse gas emissions. Perovskite solar cells (PSC) provide a low-carbon energy source, at lower production costs than traditional silicon-based solar cells. PSC's suffer some issues with long-term stability. This report presents a measurement aimed at better understanding interfacial dynamics of PSC's, using X-ray Photo-electron Spectroscopy (XPS). By collecting data at the synchrotron BESSY II, material compositions at different depths in the cell were successfully measured. An unexplained shift in binding energy was observed for configurations with an external light source on and off.

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