The invention of perovskite solar cells (PSCs) has emerged as a notable evolution in solar cell
technologies in recent times. Since its discovery in 2010, the technology has achieved the
fastest growth of solar to electrical efficiency improvement from 3.9% to over 24% in 2020.
Such solar cells are typically smaller in size and therefore have limited stability, resulting in
large scale application and long-term durability being a severe issue. An appropriate way to
address some of these challenges is by focusing higher intensity light on smaller PSCs.
In this thesis, several PSCs have been fabricated for the use of concentrated light at different
material combinations and lighting conditions to enhance their overall system performance.
The combinations include replacing lead by copper, e.g. MACuxI3 (1 ≤ x ≥ 2); partial lead
replacement, i.e. MAPb1-xCuxI3; and cocktail perovskite, i.e. both MAPbI3 and MACuxI3
mixture, are employed for a carbon-based PSC. Remarkably, Cu incorporation facilitates the
near-infrared (NIR) absorption, indicating a maximum solar spectrum absorbance. Different
perovskite sets, including MAPbI3, MACuxI3, and MAPb1-xCuxI3 perovskites using a sustainable
selected solvent involving a low-temperature process, are developed. The integration of Cu
as MAPb1-xCuxI3 results in the maximum efficiency of ~12.48%, whereas using a 1:1 cocktail
perovskite solution of MAPbI3 and MACuxI3 exhibits an average power conversion efficiency
(PCE) of ~12.85%. However, MACuxI3-based PSCs lead to insignificant efficiency degradation
as observed up to 1000 hours, whereas other devices demonstrate rapid PCE degradation
over the same period. Also, Cu-incorporation facilitates a comparatively steeper and lesser
PCE degradation rate than lead-based PSCs.
In addition, an initial assessment of the PCE enhancement of the ambient PSCs with different
architectures by externally integrating concentrated optics is carried out. The concentrated
optics exhibit efficiency improvement by ~90% under the solar irradiance of 400 W/m2
,
whereas 16% efficiency increment was observed when the solar irradiance changes to 1000
W/m2
. During optics integration, a considerable elevation of short-circuit current dramatically
facilitates the overall efficiency enhancement of the PSC.
Furthermore, a series of experiments based on different device configurations for different
concentrations of WO3–x nanoparticles and perovskites were fabricated and tested to compare
the electrical properties of the devices. Samples with increasing WO3-x showed improved
efficiency, indicating the high mobility portability of organic metal halide perovskite and the
high electron mobility of PC61BM dependent on field-impact transistor estimations.
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Additional samples with different sizes (0.3cm2 and 1cm2
) were also fabricated, resulting in a
maximum power increase for the larger solar cell. However, samples of an active area of 0.3
cm2 showed a slight increase in photovoltaic performance due to limiting the area and adding
5% WO3 without a concentrator. Thermal modelling was also developed to predict the thermal
behaviour of the solar cell with integrating optics.
In addition, large area (up to 33 cm2
) Perovskite-based modules are demonstrated to use
concentrated optical devices. This study demonstrates the successful implementation of a
high concentrating photovoltaic Fresnel lens for perovskite-based solar cells. The effect of
different working conditions such as light exposure duration, temperature and photovoltaic
performance was measured, which indicated higher temperature rise and electrical
improvement of up to 10%. The temperature measurements were verified by in-house
developed COMSOL multi-physics modelling for the integrated device. Finally, the thermal
regulation of the optically integrated solar cell devices based on an inert gaseous environment
and polymer dispersed liquid crystal (PDLC) films showed maximum efficiency improvement
up to 15% and 12%, respectively. Interestingly, the large area perovskite module also showed
the same thermal regulation pattern with PDLC ON state and PDLC OFF state with significant
Isc and maximum power values. This provides a strong rationale to control the operating
temperature of the optically integrated solar cells by the self-powered daylighting control
mechanism such as PDLC films providing an ideal candidate for the building integrated
photovoltaic applications.