Executive Summary : | The rapid growth in power conversion efficiency (PCE) of perovskite solar cell (PSC) from 3.8% to over 22% within only a few years. The application of 3D materials in PSC leads to poor long-term stability due to the hydrophilic nature of 3D perovskite materials. They are highly sensitive to temperature and moisture therefore; the organic cation of 3D halide perovskites can be easily destroyed in an ambient environment. For instance, when the 3D perovskite dimension changes to 2D, many interesting features appear with enhanced stability in the ambient environment, which significantly opens the door to different applications. Recent experimental investigations have revealed that 2D perovskites are significantly more stable than their 3D bulk. Although 2D or quasi-2D perovskite is flourishing as one of the most credible paths toward stable PSC the aforementioned issues, relating to 2D perovskite can be resolved by mixing 2D with the conventional 3D lead perovskite. Large-scale commercial manufacture and photovoltaic field applications of lead perovskites are hampered by lead toxicity concerns. However, solar cell degradation is not only due to the poor stability of the perovskite layers but can be also accelerated by the instability of the other layers of the solar cell stack. For instance, the organic hole transporting material (HTM) is unstable when in contact with water. This can be partially limited by proper device encapsulation using buffer layers between perovskite and HTM or moisture-blocking HTM. However, this approach increases the device complexity, and the cost of materials and processing. On the other hand, 2D perovskites have recently attracted substantial interest due to their superior stability and water resistance. This 2D/3D interface brings together the enhanced stability of 2D perovskite with the panchromatic absorption and excellent charge transport of the 3D ones, enabling the fabrication of efficient and ultra-stable solar cells, an important proof of concept for further device optimization and up-scaling. The interface engineering of 2D/3D perovskite, which grows forms a peculiar bottom-up phase, segregated graded structure. The unique combination of the 2D layer acting as a protective window against moisture, preserving the 3D perovskite, and the efficient 3D one provides the hint for the development of a stable perovskite technology, paving the way for the realization of near-term high efficient and stable perovskite solar cells for widespread deployment. In this context, the appropriate combination of first-principles computational and experimental approaches will be used to conduct reliable research on solar cell properties. As a result, the objective of this research would have been to learn more about the interfacial and operational mechanisms of HTM-free and lead-free 3D/2D Lead-Free Perovskites solar cells. |