Doctor of Philosophy
Intelligent Polymer Research Institute
Sae-kung, Chaiyuth, High photo-voltage multijunction polymer solar cells for water splitting, Doctor of Philosophy thesis, Intelligent Polymer Research Institute, University of Wollongong, 2017. https://ro.uow.edu.au/theses1/312
The sun is able to produce enough energy to fulfil the global energy demand. However, the intermittency of solar energy supply demands the development of suitable energy storage technologies. Photoelectrochemical devices (PECs), which harness sunlight to perform water electrolysis to produce hydrogen and oxygen, integrate a solar cell, electrocatalyst and electrolyte to achieve chemical energy storage. Constructing a PEC device, it is necessary to consider that water electrolysis requires at least 1.23 V. Moreover, characteristics such as being up-scalable, using abundant materials, being low-cost, robustness and high efficiency are essential for the PEC to be industrialised. Polymer solar cells (PSCs) are promising technologies for the PV component due to their anticipated low-cost and solution processability. However, the highest reported photovoltage single junction PSC is still below the minimum voltage required for water electrolysis.
To solve this issue, tandem structures can increase the photovoltage in a costeffective manner and methodology to achieve this without raising the material/manufacturing cost significantly. The challenge remains to find materials that possess these characteristics and that can be optimised for both optical and electronic properties for thin multilayer stacking by solution processing without damaging the underlying layers.
There is a need to develop the interfacial layer between the two junctions which constitute the tandem structure, charge carrier collection efficiency, work function alignment, and reduction of charge recombination. These parameters are directly related to the PSC efficiency, especially the VOC. With these points of view, this thesis aims to fabricate, optimise, and characterise polymer tandem solar cells with high photovoltage; beyond the required potential for water electrolysis, with reduced dependence on in vacuo processing, through an effective solution processable interfacial layer. A summary of the realisation of these aims are presented in the following paragraphs...
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