Browsing by Author "Sidhik, Siraj"

Now showing 1 - 5 of 5
  • Thumbnail Image
    Item
    Halide perovskites for high-efficiency and durable photovoltaics
    (2023-04-20) Sidhik, Siraj; Mohite, Aditya D
    Perovskite solar cells have gained significant attention in recent years due to their potential as a low-cost and highly efficient alternative to traditional silicon-based solar cells. In particular, 3D perovskites have shown exceptional performance in solar cells, but their stability remains a concern. To address this issue, researchers have been exploring the use of 2D perovskites, which offer enhanced stability due to their reduced dimensionality. This thesis aims to investigate the role of 2D perovskites in enhancing the efficiency and stability of 3D perovskite solar cells, as well as exploring the combination of 3D/2D perovskites to further enhance the efficiency and stability of the solar cells. The thesis presents a simple and scalable approach for the fabrication of 2D perovskite thin films with a homogenous layer thickness, termed as the "phase-selective method". This method involves the dissolution of single-crystalline powders with a homogeneous perovskite layer thickness in desired solvents to fabricate thin films. In situ characterizations reveal the presence of sub-micrometer-sized seeds in solution that preserve the memory of the dissolved single crystals and dictate the nucleation and growth of grains with an identical thickness of the perovskite layers in thin films. This approach can lead to the production of high-quality 2D perovskite thin films, which can enhance the stability and efficiency of solar cells. In the second part, the thesis presents a study on the development of highperformance 2D perovskite solar cells using Li-doped nickel oxide (NiOX) as a hole transport layer (HTL). The incorporation of Li-doped NiOX significantly improves the morphology, crystallinity, and orientation of 2D perovskite films and affords a superior band alignment, facilitating efficient charge extraction. Furthermore, 2D PSCs with Li-doped NiOX exhibit excellent photostability without the need for external thermal management, which is a significant advantage for practical applications. Finally, the thesis addresses the challenge of achieving solution-processed heterostructures in halide perovskites by developing a new approach to grow phasepure 2D halide perovskite stacks of the desired composition, thickness, and bandgap onto 3D perovskites without dissolving the underlying substrate. The resulting 3D/2D bilayer exhibited a high photovoltaic efficiency and exceptional stability, indicating that the 3D/2D bilayer inherits the intrinsic durability of 2D perovskite without compromising efficiency. Overall, this thesis presents several significant contributions towards the development of highly efficient and stable perovskite solar cells. The phase-selective method for fabricating 2D perovskite thin films can lead to the production of high quality 2D perovskites, while the use of Li-doped NiOX as an HTL can significantly improve the efficiency and stability of 2D perovskite solar cells. Additionally, the development of a new approach to grow 2D halide perovskite stacks onto 3D perovskites can pave the way for future developments in the field of perovskite solar cells. These findings have significant implications for the development of a clean energy future.
  • Thumbnail Image
    Item
    High-phase purity two-dimensional perovskites with 17.3% efficiency enabled by interface engineering of hole transport layer
    (Elsevier, 2021) Sidhik, Siraj; Wang, Yafei; Li, Wenbin; Zhang, Hao; Zhong, Xinjue; Agrawal, Ayush; Hadar, Ido; Spanopoulos, Ioannis; Mishra, Anamika; Traoré, Boubacar; Samani, Mohammad H. K.; Katan, Claudine; Marciel, Amanda B.; Blancon, Jean-Christophe; Even, Jacky; Kahn, Antoine; Kanatzidis, Mercouri G.; Mohite, Aditya D.
    State-of-the-art p-i-n-based 3D perovskite solar cells (PSCs) use nickel oxide (NiOX) as an efficient hole transport layer (HTL), achieving efficiencies >22%. However, translating this to phase-pure 2D perovskites has been unsuccessful. Here, we report 2D phase-pure Ruddlesden-Popper BA2MA3Pb4I13 perovskites with 17.3% efficiency enabled by doping the NiOX with Li. Our results show that progressively increasing the doping concentration transforms the photoresistor behavior to a typical diode curve, with an increase in the average efficiency from 2.53% to 16.03% with a high open-circuit voltage of 1.22 V. Analysis reveals that Li doping of NiOX significantly improves the morphology, crystallinity, and orientation of 2D perovskite films and also affords a superior band alignment, facilitating efficient charge extraction. Finally, we demonstrate that 2D PSCs with Li-doped NiOX exhibit excellent photostability, with T99 = 400 h at 1 sun and T90 of 100 h at 5 suns measured at relative humidity of 60% ± 5% without the need for external thermal management.
  • Thumbnail Image
    Item
    Highly efficient photoelectric effect in halide perovskites for regenerative electron sources
    (Springer Nature, 2021) Liu, Fangze; Sidhik, Siraj; Hoffbauer, Mark A.; Lewis, Sina; Neukirch, Amanda J.; Pavlenko, Vitaly; Tsai, Hsinhan; Nie, Wanyi; Even, Jacky; Tretiak, Sergei; Ajayan, Pulickel M.; Kanatzidis, Mercouri G.; Crochet, Jared J.; Moody, Nathan A.; Blancon, Jean-Christophe; Mohite, Aditya D.
    Electron sources are a critical component in a wide range of applications such as electron-beam accelerator facilities, photomultipliers, and image intensifiers for night vision. We report efficient, regenerative and low-cost electron sources based on solution-processed halide perovskites thin films when they are excited with light with energy equal to or above their bandgap. We measure a quantum efficiency up to 2.2% and a lifetime of more than 25 h. Importantly, even after degradation, the electron emission can be completely regenerated to its maximum efficiency by deposition of a monolayer of Cs. The electron emission from halide perovskites can be tuned over the visible and ultraviolet spectrum, and operates at vacuum levels with pressures at least two-orders higher than in state-of-the-art semiconductor electron sources.
  • Thumbnail Image
    Item
    Long periodic ripple in a 2D hybrid halide perovskite structure using branched organic spacers
    (Royal Society of Chemistry, 2020) Hoffman, Justin M.; Malliakas, Christos D.; Sidhik, Siraj; Hadar, Ido; McClain, Rebecca; Mohite, Aditya D.; Kanatzidis, Mercouri G.
    Two-dimensional (2D) halide perovskites have great promise in optoelectronic devices because of their stability and optical tunability, but the subtle effects on the inorganic layer when modifying the organic spacer remain unclear. Here, we introduce two homologous series of Ruddlesden–Popper (RP) structures using the branched isobutylammonium (IBA) and isoamylammonium (IAA) cations with the general formula (RA)2(MA)n−1PbnI3n+1 (RA = IBA, IAA; MA = methylammonium n = 1–4). Surprisingly, the IAA n = 2 member results in the first modulated 2D perovskite structure with a ripple with a periodicity of 50.6 Å occurring in the inorganic slab diagonally to the [101] direction of the basic unit cell. This leads to an increase of Pb–I–Pb angles along the direction of the wave. Generally, both series show larger in-plane bond angles resulting from the additional bulkiness of the spacers compensating for the MA's small size. Larger bond angles have been shown to decrease the bandgap which is seen here with the bulkier IBA leading to both larger in-plane angles and lower bandgaps except for n = 2, in which the modulated structure has a lower bandgap because of its larger Pb–I–Pb angles. Photo-response was tested for the n = 4 compounds and confirmed, signaling their potential use in solar cell devices. We made films using an MACl additive which showed good crystallinity and preferred orientation according to grazing-incidence wide-angle scattering (GIWAXS). As exemplar, the two n = 4 samples were employed in devices with champion efficiencies of 8.22% and 7.32% for IBA and IAA, respectively.
  • Thumbnail Image
    Item
    Revealing the impact of ammonium ions from different low-dimensional perovskite structures on the film formation and degradation mechanism of FAPbI3 via sequential deposition
    (AIP Publishing LLC, 2024) Wang, Yafei; Yuan, Shihao; Feng, Rongsen; Diao, Zecheng; Huang, Jie; Liao, Jiacai; Sidhik, Siraj; Shuai, Xinting; Wang, Meicong; Zou, Tao; Liang, Zhongwei; Zhang, Ting; Mohite, Aditya D.; Li, Shibin
    In recent years, the organic–inorganic hybrid perovskite community has been widely employed as the photo-active layer in optical-electronic devices. The black α-phase formamidinium lead iodide (FAPbI3) is the most popular perovskite for realizing high-efficiency solar cells due to its suitable bandgap. However, the issue of stability is also a concern in the research on FAPbI3 solar cells. In this study, different ammonium ions, such as butylamine (BA), guanidine (GA), and butylene diamine (BDA), which are commonly used to construct two-dimensional perovskites, including Ruddlesden–Popper, Dion–Jacobson, and alternating cations in the interlayer space, respectively, were introduced in the fabrication of FAPbI3 using a sequential deposition method. Several structures of PbI2 precursor films were formed by introducing the aforementioned ions, which exhibited different arrangements and connection modes in lead iodides. BA-PbI2 precursor films exhibited higher specific surface areas, which were beneficial to the diffusion, ion exchange, and sequential reaction of FA+. The BDA-PbI2 precursor film slowed down the sequential reaction of FAPbI3 because of reduced van der Waals bonds. The nucleation dynamics and degradation processes of perovskites were deeply investigated in this study. Solar cells based on BA-PbI2, GA-PbI2, and BDA-PbI2 were also fabricated.