Perovskite solar cells soon after their emerging started to grow very fast because of their spectacular properties and simplicity of their processing. These cells are able to be fabricated very cheap with wet techniques. These features caused to gain lots of attention and being one of the hot topics in the solar harvesters’ field. Currently, the state of the art efficiency is greater than 25%, which is approaching the most efficient solar cells. However, there are some drawbacks which have to be addressed to make these cells commercially available. Two main problems are stability and Hysteresis. In order to overcome these problems there are ongoing researches to find a way to reduce them. Here in this study we are focusing on finding new material for replacing currently used carrier transporting layers, in order to improve the perovskite cell performance. The material which has been studied is the reduced Graphene Oxide (rGO). Reduced Graphene Oxide has shown capability to be a good candidate for the cell performance improvement. This thesis has two major steps, in the first step the aim was to realize a very good graphene oxide (GO) deposition on transparent conductive oxide (TCO) electrode with a good coverage, low defect, thickness controllability and reproducibility. This step have been done with different wet techniques like: Spin coating, Drop casting and Vacuum filtration. Priority was wet techniques, because of lowering the overall price and manufacturing complexity. This step also was included investigating of the prepared samples with Raman, SEM and UV-Visible Spectroscopy. Later, the best samples were subjected to be characterized by XRD, UPS and XPS. Afterward, the optimized GO has been reduced to achieve a good conductivity. Reduction has been done chemically, electrochemically and by heat annealing. The second step was whole cell fabrication which starts with deposition of Perovskite layer. This deposition has been done with two different techniques spin coating and vacuum evaporation. In the end, as prepared devices have been tested and the performance was checked with solar simulator. Results have shown using rGO as a hole transporting layer can reduce hysteresis also in the fast scan rate.
Poco dopo la loro apparizione le celle solari a perovskite sono divenute popolari a causa delle loro proprietà spettacolari e la semplicità del loro trattamento. Queste celle possono essere fabbricate a basso costo con tecniche “bagnate”, in fase liquida. Per queste caratteristiche queste celle sono uno dei temi caldi nel campo della conversione fotovoltaica'. Attualmente lo stato dell'arte per l’efficienza è superiore al 25%, un valore che si avvicina alle celle solari più efficienti. Tuttavia, ci sono alcuni problemi che devono risolti per rendere queste cellule disponibili in commercio. Due problemi principali sono la stabilità e l’isteresi. Al fine di superare questi problemi ci sono ricerche in corso per trovare un modo per ridurli. Questo studio riguarda la ricerca di nuovi materiali per la sostituzione di strati attualmente in uso che trasportano i portatori di carica, al fine di migliorare le prestazioni delle celle a perovskite. Il materiale studiato è ossido di grafene (RGO). L’RGO ha dimostrato la capacità di essere un buon candidato per il miglioramento delle prestazioni delle celle. Questa tesi ha due fasi principali, nella prima fase lo scopo è realizzare un ossido di grafene di buona qualità per deposizione su un elettrodo trasparente (TCO) con una buona copertura, bassa concentrazione di difetti, controllabilità dello spessore e riproducibilità. Allo scopo sono state utilizzate diverse tecniche come: spin coating, fusione goccia e filtrazione a vuoto.I materiaoli prodotti sono stati caratterizzati con Raman, SEM e spettroscopia UV-Visibile. Poi i migliori campioni sono stati sottoposti a caratterizzarsi con XRD, UPS e XPS. In seguito, il GO ottimizzato è stato ridotto per ottenere una buona conducibilità. mediante l'uso di reagenti chimici, o per via elettrochimica e ricottura di calore. Il secondo passo è stato la fabbricazione delle celle che inizia con la deposizione di perovskite. Questo deposito è stato fatto con due diverse tecniche, spin coating o evaporazione sottovuoto. Alla fine, i dispositivi preparati sono stati testati con un simulatore solare. I risultati hanno dimostrato che utilizzando rGO come strato trasporto per le lacune è possibile ridurre l'isteresi anche nelle misure I-V veloci.
Perovskite solar cell with reduced graphene oxide integration
KASHI, AMIR ABBAS
2015/2016
Abstract
Perovskite solar cells soon after their emerging started to grow very fast because of their spectacular properties and simplicity of their processing. These cells are able to be fabricated very cheap with wet techniques. These features caused to gain lots of attention and being one of the hot topics in the solar harvesters’ field. Currently, the state of the art efficiency is greater than 25%, which is approaching the most efficient solar cells. However, there are some drawbacks which have to be addressed to make these cells commercially available. Two main problems are stability and Hysteresis. In order to overcome these problems there are ongoing researches to find a way to reduce them. Here in this study we are focusing on finding new material for replacing currently used carrier transporting layers, in order to improve the perovskite cell performance. The material which has been studied is the reduced Graphene Oxide (rGO). Reduced Graphene Oxide has shown capability to be a good candidate for the cell performance improvement. This thesis has two major steps, in the first step the aim was to realize a very good graphene oxide (GO) deposition on transparent conductive oxide (TCO) electrode with a good coverage, low defect, thickness controllability and reproducibility. This step have been done with different wet techniques like: Spin coating, Drop casting and Vacuum filtration. Priority was wet techniques, because of lowering the overall price and manufacturing complexity. This step also was included investigating of the prepared samples with Raman, SEM and UV-Visible Spectroscopy. Later, the best samples were subjected to be characterized by XRD, UPS and XPS. Afterward, the optimized GO has been reduced to achieve a good conductivity. Reduction has been done chemically, electrochemically and by heat annealing. The second step was whole cell fabrication which starts with deposition of Perovskite layer. This deposition has been done with two different techniques spin coating and vacuum evaporation. In the end, as prepared devices have been tested and the performance was checked with solar simulator. Results have shown using rGO as a hole transporting layer can reduce hysteresis also in the fast scan rate.File | Dimensione | Formato | |
---|---|---|---|
Master Thesis-final.pdf
accessibile in internet per tutti
Descrizione: Thesis text
Dimensione
5.11 MB
Formato
Adobe PDF
|
5.11 MB | Adobe PDF | Visualizza/Apri |
I documenti in POLITesi sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
https://hdl.handle.net/10589/131523