Perovskite Solar Cells Integrated with Concentrated Optics: Materials to Devices

Abstract

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. 3 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.