Ionic liquid based dye-sensitized solar cells (DSSCs) were exposed to outdoor irradiation for seven months in Ljubljana (April-October, 906 kWh/m2) under short-circuit, open-circuit, and quasi maximum-power-point regime. As a reference we kept a series of DSSCs in the dark at room temperature under open-circuit regime. The performance of the DSSCs was evaluated indoor under standard test conditions prior to ageing, twice during ageing and after ageing. Additionally, the electroluminescence and transmittance imaging were used to follow the evolution of local defects with ageing. Operating condition has a strong influence on the ageing of DSSCs but despite this the performance of DSSCs remained remarkably stable. The exceptions were cells aged under short-circuit condition, which led to a significant decrease in short-circuit current. This resulted from the degradation of the dye molecules and a decrease in the tri-iodide concentration in the electrolyte.
COBISS.SI-ID: 10268756
Ionic liquid based dye-sensitized solar cells (DSSCs) were exposed to outdoor irradiance for seven months (906 kWh/m2) on faculty’s roof in Ljubljana at short circuit, open circuit, and quasi maximum power point condition. During the ageing we also kept the reference DSSCs in the dark at room temperature under open circuit condition. The performance of DSSCs was evaluated indoor at standard test conditions before ageing, two times during the ageing and after aging. Additionally, the electroluminescence and transmittance imaging were used to follow the evolution of local defects upon ageing. The results revealed that operating condition has a strong influence on the ageing of the DSSCs. The performance of DSSCs remained remarkably stable with an exception of the cells aged under short circuit condition which caused a significant decrease in short-circuit current mainly due to a decrease of tri-iodide concentration in the electrolyte.
COBISS.SI-ID: 9544788
The recombination reactions in the dye-sensitized solar cells (DSSCs) are extremely complex since many different recombination paths simultaneously exist. They all affect the open circuit voltage (Voc) vs. illumination intensity (G) dependence. In the literature many contradictive results about the dVoc/dlog(G) gradient exist. In order to resolve the discrepancies we have studied the influence of the thickness of the active layer and temperature dependence along with tri-iodide concentration on the dVoc/dlog(G) gradient. The results revealed that the thickness of the active layer has only a small effect on the gradient. Contrary, the gradient very strongly depends on the cell temperature and tri-iodide concentration. The gradient could be only 60 mV/decade when the concentration and the cell temperature are low (when the DSSC is diffusion limited) and it could exceed 130 mV/decade at higher concentrations and higher temperatures (when recombinations prevails). Additionally, the open circuit voltage temperature coefficient of the DSSCs having different tri-iodide concentration has been measured at different light intensities. The absolute value of the dVoc/dT increases with tri-iodide concentration in the electrolyte and with decreasing light intensity which is both associated with a higher probability of the recombinations.
COBISS.SI-ID: 8807508