Engineering carbon electrodes for hole-transport-layer-free perovskite solar cells
3.07 MB
avoin
Julkaisu on tekijänoikeussäännösten alainen. Teosta voi lukea ja tulostaa henkilökohtaista käyttöä varten. Käyttö kaupallisiin tarkoituksiin on kielletty.
Lataukset1
Pysyvä osoite
Verkkojulkaisu
DOI
Tiivistelmä
Perovskite solar cells (PSCs) are an emerging photovoltaic technology, demonstrating high power conversion efficiencies. Hole-transport-layer-free (HTL-free) carbon-based PSCs offer advantages of high stability, low material costs, and scalable fabrication techniques, but often face problems with low efficiencies due to poor interface between the perovskite absorber and the carbon electrode. Another advantage of HTL-free carbon-based PSCs is the possibility of recycling them through a facile “revival” process that allows the reuse of the mesoporous scaffold. However, the efficiency of the revival route depends on the integrity of the top carbon electrode. Thus, carbon electrode engineering is of high importance to manufacture efficient, stable, and robust carbon electrodes for HTL-free PSCs.
In this thesis carbon pastes with different inorganic binders were studied to elucidate their effect on power conversion efficiency (PCE), stability, and revival rates of PSCs. Carbon pastes with combinations of ZrO2 and CuO, MoO2, NiO, WO2, WO3 were manufactured and used to fabricate carbon electrodes for HTL-free PSCs. Carbon electrodes were then characterised with scanning electron microscopy, energy-dispersive X-ray spectroscopy, and 4-point probe conductivity
measurements. The performance characteristics of manufactured devices were obtained via current-voltage curves and electrochemical impedance spectroscopy. Stability of fabricated cells was assessed through a high-humidity dark storage test. Lastly, revival treatment using γ-valerolactone was applied to the cells and their performance before and after revival was assessed and compared.
Cells with a combination of ZrO2 and WO3 were found to have the highest average PCE of 8.8%, closely followed by devices with ZrO2 and NiO with PCE of 8.7%. Incorporation of CuO and MoO2 into the carbon paste had a detrimental effect on photovoltaic performance, resulting in PCE of 4% and 1.9%, respectively. The performance of cells with CuO and MoO2 decreased rapidly during the high humidity stability test, while the rest of the studied devices exhibited high stability to environmental moisture. Electrodes with MoO2 detached from the substrate after the revival treatment, while the rest of fabricated electrodes did not show signs of degradation. Revival rates of devices showed high variance between the samples due to variations in the solvent quality.
The results show that the choice of inorganic binders in the carbon paste has an influence on devices performance and stability. Further studies can build upon the present study and investigate the combined effect of champion inorganic binder mixtures with variations of other carbon paste components. Moreover, the results highlight the need for further optimization of the revival treatment of HTL-free carbon-based PSCs.