|dc.description.abstract||Dye-sensitised solar cells (DSSCs) and perovskite solar cells (PSCs) have brought new
impetus to the photovoltaic research field due to their artistry such as colour and
flexibility, and stable performance under low-intensity light. These solar cells adopt a
common architecture of <electron transport layer / light absorber layer / electrolyte or
hole transport layer>, however show distinct features owing to the different light
absorber materials, i.e. a donor-acceptor type dye for the DSSC and a metal-halide
perovskite for the PSC.
One of the remaining challenges for the DSSC and PSC is their long-term stability.
Leakage of the volatile electrolyte especially in DSSCs has pushed the field towards
developing solid-state hole transport materials (HTMs). However, depositing the HTM
in DSSCs has often led to poor interfaces, lowering the performance of the cell. PSCs
have overcome this challenge by increasing the thickness of the perovskite layer, but
have suffered from shorter shelf-lifetime than DSSCs, owing to the instability of the
perovskite material against moisture and ion migration within the cell.
This thesis explores the solution towards highly efficient and stable DSSCs or PSCs,
by taking a broad approach for both solar cells with a focus on the <electrolyte or
HTM> layer. Our first study (Chapter 3) investigates a previously reported copper
bipyridyl electrolyte in respect to the standard iodide/triiodide electrolyte in DSSCs.
We demonstrate that the copper bipyridyl DSSCs reach high photovoltages over 1.0
V, with co-sensitised devices attaining power conversion efficiencies (PCE) over 9%
at 1 sun, 10% at 0.1 sun, and 29% at 1000 lux. Owing to the low-cost 5T dye co-sensitised with the efficient XY1 dye, the cost performance was found to be improved.
These copper bipyridyl DSSCs are known for their ability to be turned into solid-state
cells by slowly drying out the electrolyte, which leads to our second study (Chapter
4) on solid-state polyiodide DSSCs. Here we demonstrate that a novel solid-state
polyiodide (Ply-I) DSSC can be produced from a standard iodide/triiodide electrolyte.
These solid-state cells reached a stabilised maximum PCE of 5.0% compared to the
corresponding liquid-state cells at maximum 5.7%. The Ply-I cell was shown to be
stable over 8000 h without encapsulation. Our third study (Chapter 5) moves onto
PSCs. A novel monothiatruxene-based organic HTM (TrxS-2MeOTAD) was
synthesised and demonstrated to work as efficiently as the standard Spiro-MeOTAD
HTM (~19%), and with higher operational stability. In our last study (Chapter 6) we
investigate copper iodide complexes as dopant-free organometallic HTM candidates
in PSCs. This unique class of HTMs has led to relatively low performance (maximum
6.5%) than predicted from their conductivity, apparently due to the poor interface and
grain boundaries observed in the fabricated PSCs.
Overall, we believe that the approach and results described in this thesis will provide
useful insights in designing alternative electrolytes and HTMs to achieve highly
practical DSSCs and PSCs.||en
|dc.publisher||The University of Edinburgh||en
|dc.relation.hasversion||Ellie Tanaka, and Neil Robertson, “Polyiodide solid-state dye-sensitized solar cell produced from a standard liquid I- /I3 - electrolyte”, J. Mater. Chem. A, 2020, 8, 19991– 19999. (2020).||en
|dc.relation.hasversion||Ellie Tanaka, Hannes Michaels, Marina Freitag, Neil Robertson, “Synergy of co sensitizers in a copper bipyridyl redox system for efficient and cost-effective dye sensitized solar cells in solar and ambient light”, J. Mater. Chem. A, 2020, 8, 1279- 1287.||en
|dc.relation.hasversion||John Marques dos Santos, Ellie Tanaka, Alan Wiles, Graeme Cooke and Neil Robertson, “Donor-free oligothiophene based dyes with di-anchor architecture for dye-sensitized solar cells”, Mol. Syst. Des. Eng., 2021, DOI: 10.1039/d1me00009h||en
|dc.relation.hasversion||Maxim S. Mikhailov, Nikita S. Gudim, Ekaterina A. Knyazeva, Ellie Tanaka, Lu Zhang, Ludmila V. Mikhalchenko, Neil Robertson, Oleg A. Rakitin, “9-(p-Tolyl)- 2,3,4,4a,9,9a-hexahydro-1H-carbazole – a new donor building-block in the design of sensitizers for dye-sensitized solar cells”, J. Photochem. Photobiol. A, 2020, 391, 112333.||en
|dc.relation.hasversion||Timofey N. Chmovzh, Ekaterina A. Knyazeva, Ellie Tanaka, Vadim V. Popov, Ludmila V. Mikhalchenko, Neil Robertson, Oleg A. Rakitin, “[1,2,5]Thiadiazolo[3,4- d]pyridazine as an internal acceptor in the D-A-π-A organic sensitizers for dye sensitized solar cells”, 2019, Molecules, 24, 1588.||en
|dc.title||From electrolytes to hole transport materials in dye-sensitised and perovskite solar cells||en
|dc.type||Thesis or Dissertation||en
|dc.type.qualificationname||PhD Doctor of Philosophy||en