Inverted organic photovoltaic device with a new electron transport layer

We demonstrate that there is a new solution-processed electron transport layer, lithium-doped zinc oxide (LZO), with high-performance inverted organic photovoltaic device. The device exhibits a fill factor of 68.58%, an open circuit voltage of 0.86 V, a short-circuit current density of −9.35 cm/mA(2) along with 5.49% power conversion efficiency. In addition, we studied the performance of blend ratio dependence on inverted organic photovoltaics. Our device also demonstrates a long stability shelf life over 4 weeks in air

Preparation of hydrogen, fluorine and chlorine doped and co-doped titanium dioxide photocatalysts: a theoretical and experimental approach

Titanium dioxide (TiO2) has a strong photocatalytic activity in the ultra-violet part of the spectrum combined with excellent chemical stability and abundance. However, its photocatalytic efficiency is prohibited by limited absorption within the visible range derived from its wide band gap value and the presence of charge trapping states located at the band edges, which act as electron-hole recombination centers. Herein, we modify the band gap and improve the optical properties of TiO2via co-doping with hydrogen and halogen. The present density functional theory (DFT) calculations indicate that hydrogen is incorporated in interstitial sites while fluorine and chlorine can be inserted both as interstitial and oxygen substitutional defects. To investigate the synergy of dopants in TiO2 experimental characterization techniques such as Fourier transform infrared (FTIR), X-ray diffraction (XRD), X-ray and ultra-violet photoelectron spectroscopy (XPS/UPS), UV-Vis absorption and scanning electron microscopy (SEM) measurements, have been conducted. The observations suggest that the oxide’s band gap is reduced upon halogen doping, particularly for chlorine, making this material promising for energy harvesting devices. The studies on hydrogen production ability of these materials support the enhanced hydrogen production rates for chlorine doped (Cl:TiO2) and hydrogenated (H:TiO2) oxides compared to the pristine TiO2 reference

Organohalide Lead Perovskites for Photovoltaic Applications

Perovskite solar cells have recently exhibited a significant leap in efficiency due to their broad absorption, high optical absorption coefficient, very low exciton binding energy, long carrier diffusion lengths, efficient charge collection, and very high open-circuit potential, similar to that of III-IV semiconductors. Unlike silicon solar cells, perovskite solar cells can be developed from a variety of low-temperature solutions processed from inexpensive raw materials. When the perovskite absorber film formation is optimized using solvent engineering, a power conversion efficiency of over 21% has been demonstrated, highlighting the unique photovoltaic properties of perovskite materials. Here, we review the current progress in perovskite solar cells and charge transport materials. We highlight crucial challenges and provide a summary and prospects

Dimensionality engineering of hybrid halide perovskite light absorbers

Hybrid halide perovskite solar cells were first demonstrated in 2009 with cell efficiency quickly soaring from below 10% to more than 23% in a few years. Halide perovskites have the desirable processing simplicity but are very fragile when exposed to water and heat. This fragility represents a great challenge for the achievement of their full practical potential in photovoltaic technologies. To address this problem, here we review the recent development of the mixed-dimensional perovskites, whereby the trade-off between power conversion efficiency and stability of the material can be finely tuned using organic amine cations with different sizes and functionalities

New Horizons for Perovskite Solar Cells Employing DNA-CTMA as the Hole-Transporting Material

We investigate solution-processed low-temperature lead-halide perovskite solar cells employing deoxyribose nucleic acid (DNA)-hexadecyl trimethyl ammonium chloride (CTMA) as the hole-transport layer and (6,6)-phenyl C-61-butyric acid methyl ester (PCBM) as electron-acceptor layer in an inverted p-i-n device configuration. The perovskite solar cells utilizing a bio-based charge-transport layer demonstrate power conversion efficiency values of 15.86%, with short-circuit current density of 20.85mAcm(-2), open circuit voltage of 1.04V, and fill factor of 73.15%, and improved lifetime. DNA-based devices maintained above 85% of the initial efficiency after 50days in air

Sn‐Based Perovskite Halides for Electronic Devices

Because of its less toxicity and electronic structure analogous to that of lead, tin halide perovskite (THP) is currently one of the most favorable candidates as an active layer for optoelectronic and electric devices such as solar cells, photodiodes, and field-effect transistors (FETs). Promising photovoltaics and FETs performances have been recently demonstrated because of their desirable electrical and optical properties. Nevertheless, THP's easy oxidation from Sn2+ to Sn4+, easy formation of tin vacancy, uncontrollable film morphology and crystallinity, and interface instability severely impede its widespread application. This review paper aims to provide a basic understanding of THP as a semiconductor by highlighting the physical structure, energy band structure, electrical properties, and doping mechanisms. Additionally, the key chemical instability issues of THPs are discussed, which are identified as the potential bottleneck for further device development. Based on the understanding of the THPs properties, the key recent progress of THP-based solar cells and FETs is briefly discussed. To conclude, current challenges and perspective opportunities are highlighted.11Ysciescopu

Passivation and process engineering approaches of halide perovskite films for high efficiency and stability perovskite solar cells

The surface, interfaces and grain boundaries of a halide perovskite film carry critical tasks in achieving as well as maintaining high solar cell performance due to the inherently defective nature across their regime. Passivating materials and felicitous process engineering approaches have significant ramifications in the resultant perovskite film, and the solar cell's overall macroscale properties as they dictate structural and optoelectronic properties. Herein, we exploit a vast number of defect engineering approaches aiming to increase the performance and the stability of perovskite solar cells, especially against humidity, continuous illumination, and heat. This review begins with the perovskite materials' fundamental structural properties followed by the advances made to induce higher stabilization in perovskite solar cells by fine-tuning materials chemistry design parameters. We continue by summarizing defect passivation strategies based on molecular entities' application, including suitable functional groups that enable sufficient surface, bulk and grain boundary passivation, morphology, and crystallinity control. We also present methods to control the density of defects through the variation of processing conditions, solvent annealing and solvent engineering approaches, gas-assisted deposition methods, and use of self-assembled monolayers, as well as colloidal engineering and coordination surface chemistry. Finally, we give our perspective on how a combined understanding of materials chemistry aspects and passivation mechanisms will further develop high-efficiency and stability perovskite solar cells