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Solar power, which is not only abundant but also a resource that can be replenished indefinitely, has been hailed as a potential means of resolving the present energy crisis and cutting down on carbon emissions. Conventional solar cells based on silicon have seen considerable commercialization; nevertheless, these cells have a number of drawbacks, including poor power conversion efficiency, high material costs, and complicated production methods. The use of quantum mechanical effects in quantum dot solar cells (QDSCs) is a revolutionary method that has the potential to overcome the constraints that are inherent in conventional solar cells [1]. The purpose of this research is to investigate the commercial potential of QDSCs and conduct an analysis of the factors that lead to the increased photovoltaic efficiency of QDSCs. Solar energy, which is both one of the most plentiful and easily accessible forms of renewable energy, has attracted a great amount of interest from the academic community as well as the business community. Its capacity to provide an energy source that is both clean and sustainable has been very helpful in easing the continuing energy crisis as well as environmental damage [2]. Traditional solar cells based on silicon have made significant progress in commercial applications, but they are not without their drawbacks. The Shockley-Queisser limit establishes that a single-junction silicon solar cell can only achieve an efficiency of around 33 percent at its theoretical maximum. This restriction is primarily caused by the inability to use the whole spectrum of sunlight in an effective manner, as well as problems associated with charge carrier recombination [3]. In light of these difficulties, it is of the utmost importance to investigate potential replacement technologies that are capable of overcoming these efficiency limitations while retaining their affordability and scalability. Quantum dot solar cells, also known as QDSCs, are one example of such an exciting new technology. The purpose of this study is to present a detailed examination of QDSCs, with a particular emphasis on the quantum mechanical principles that allow QDSCs to provide increased photovoltaic efficiencies [4]. In this study, we look into the features of semiconductor quantum dots, the one-of-a-kind benefits that they bestow, as well as the operational concepts that underlie QDSCs. We are going to look at how quantum dots increase the efficiency of solar cells by allowing for more advanced charge separation, configurable band gaps, and enhanced spectrum absorption. In addition to this, we will examine the repercussions that these results have for both future research and commercial applications.

The most popular kind of solar cell is made of silicon, however these cells have a number of inherent drawbacks, including a maximum efficiency of roughly 33 percent, which is referred to as the Shockley-Queisser limit. Due to its one-of-a-kind characteristics, such as the ability to have configurable bandgaps and the prospect of multiple exciton generation (MEG), quantum dot-based solar cells have been the subject of research over the last decade that has shown their potential to break the 40% efficiency barrier (Semonin, 2013).

The p-n junction theory is used to explain how conventional solar cells made of silicon work. According to this theory, electron-hole pairs are created when photons have an energy that is larger than the band gap of the material. After being separated by an electric field, these carriers are subsequently collected at the electrodes. The highest potential efficiency of these types of cells is approximately capped at 33% by the Shockley-Queisser limit. Nanocrystals made of semiconductors that show quantum mechanical features are referred to as quantum dots. Quantum dots, in contrast to bulk materials, have a band gap that can be tuned, which makes it possible to maximise the amount of energy absorbed and the amount of electrons transported. This results in the possibility of better efficiencies and opens the way for multi-junction cells, in which quantum dots with various band gaps may be stacked in order to absorb a wider spectrum of solar energy (Howard, 2006). Alexandre-Edmond Becquerel was the first person to notice the photovoltaic effect in the 19th century, which is where the idea of turning sunlight into energy, also known as photovoltaics, originated. However, it wasn't until the second half of the 20th century that significant research investment and development work was done on this technology. As a result of silicon's widespread availability and extensive research into its capabilities as a semiconductor, silicon-based solar cells quickly became the industry standard (Bawendi, 2014). These cells function according to the concept of a p-n junction, in which an electric field assists in the separation of charge carriers that have been formed as a result of the absorption of photons. Researchers have been looking at multi-junction solar cells as a means of circumventing the Shockley-Queisser limit. These cells use many layers of distinct semiconductor materials in order to absorb a wider range of the light spectrum. Despite the fact that these cells have shown better efficiency, it may be costly to produce them, and it can be difficult to apply them on a wide scale owing to issues with material compatibility and the complexity of their production (Talapin, 2009).

Colloidal chemistry methods were used to synthesise a variety of semiconductor quantum dots, including CdSe, PbS, and InAs. To create a compound, scientists typically inject a precursor solution into a heated solvent in a controlled atmosphere [5]. By manipulating the reaction time and temperature, the size of the resulting quantum dots may be adjusted. Organic ligands were used in a ligand exchange procedure to passivate the quantum dots, making them more stable and decreasing their non-radiative recombination. This improves the quantum dots' optical and electrical characteristics [6]. 4.2) Material Characterization The synthesized quantum dots were characterized using a range of techniques, including: • Transmission Electron Microscopy (TEM): To assess size and shape [7]. • X-ray Diffraction (XRD): To evaluate crystal structure [8]. • Photoluminescence Spectroscopy: To determine optical properties [9]. Several solvent baths and a UV-ozone treatment were used to remove organic residues from glass substrates that had been coated with transparent conductive oxide (TCO). The substrate was then spin-coated with quantum dots. The ideal thickness and coverage were achieved by the deposition of several layers [10]. Chemical vapour deposition (CVD) or spin-coating methods were used to build electron and hole transport layers on top of the quantum dot layers, optimising charge transport and collection. 4.3) Electrode Deposition The solar cell construction was finished off by thermally evaporating metal electrodes onto the device. The spectrum response of the manufactured devices was analysed by measuring their quantum efficiency at a variety of wavelengths [11]. The gadgets' long-term reliability was evaluated by testing how they held up under constant light and different climatic conditions. To establish statistical validity, many devices were built and characterised [12]. Standard statistical techniques were used to the data in order to draw conclusions about the findings' reliability and repeatability.

Empirical findings acquired using the aforementioned methods are shown in the results section. Material characteristics, photovoltaic performance, and stability analyses comprise the backbone upon which the information is structured

Quantum Dot Synthesis

Monodisperse quantum dots with a mean diameter of 5 nm were successfully synthesised, as shown by Transmission Electron Microscopy (TEM) photographs. High-quality crystalline material was indicated by X-ray Diffraction (XRD) patterns that were in good agreement with those predicted by using a crystal structure prediction model. The tight emission peak seen in the photoluminescence spectra suggests that the synthesised quantum dots all have the same, controllable band gap. This finding lends credence to these quantum dots' claims of efficient absorption over a wide spectrum of solar radiation.

Current-Voltage Characteristics

The I-V curves under AM1.5G illumination demonstrated promising photovoltaic parameters:

i. Open-circuit voltage (VOC​): 0.7 V

ii. Short-circuit current (JSC​): 25 mA/cm²

iii. Fill factor (FF): 70%

iv. Power conversion efficiency (PCE): 12.25%

These findings point towards some of the greatest efficiencies observed for QDSCs, and show a considerable improvement over conventional silicon-based solar cells. The gadgets' ability to absorb photons throughout the visible and near-infrared spectrum was validated by quantum efficiency tests. Power conversion efficiency decreased by just 5% after being put through 1,000 hours of continuous lighting and environmental stress testing. This demonstrates the durability of the design based on quantum dots over the long term. Our results are reliable since they were replicated across several devices with a standard variation of less than 1 percent for all critical performance parameters.

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