Wearable devices are mainly based on plastic substrates, such as polyethylene terephthalate and polyethylene naphthalate, which causes environmental pollution after use due to the long decomposition periods. This work reports on the fabrication of a biodegradable and biocompatible transparent conductive electrode derived from bamboo for flexible perovskite solar cells. The conductive bioelectrode exhibits extremely flexible and light-weight properties. After bending 3000 times at a 4 mm curvature radius or even undergoing a crumpling test, it still shows excellent electrical performance and negligible decay. The performance of the bamboo-based bioelectrode perovskite solar cell exhibits a record power conversion efficiency (PCE) of 11.68%, showing the highest efficiency among all reported biomass-based perovskite solar cells. It is remarkable that this flexible device has a highly bendable mechanical stability, maintaining over 70% of its original PCE during 1000 bending cycles at a 4 mm curvature radius. This work paves the way for perovskite solar cells toward comfortable and environmentally friendly wearable devices.
Abstract State‐of‐the‐art, high‐performance formamidinium‐lead‐iodide‐based (FAPbI 3 ‐based) perovskite photovoltaics are mainly prepared by one‐step antisolvent dripping deposition or two‐step sequential fabrication methods. Compared with the one‐step deposition, the two‐step fabricated perovskite films tend to grow columnar perovskite grains vertically which is easier for carrier extraction and transportation. Herein, the concept of formamidinium methylammonium cesium based ternary‐cation two‐step sequential deposition method is put forward by incorporating cesium acetate (CsAc) into a lead iodide precursor, which generates CsPbI 3 crystal nuclei improving the further perovskite crystallization. When the formamidinium/methylammonium‐based organic amine salts solution is spin coated on the PbI 2 substrate, the acetate moves upward and induces perovskite orientational and uniform crystallization, which can go a step further for the vertical columnar grains achieving fewer defects and higher photovoltaic efficiency. The champion outdoor power conversion efficiency of the modified device under AM 1.5G reaches 21.50% and its indoor efficiency at 1000 lux reaches 40.99%. This work paves the way for further exploring ternary‐cation two‐step sequential deposition methods to prepare high‐performance perovskite photovoltaics.
Abstract Compared with red and green perovskite light‐emitting diodes (PeLEDs), blue PeLEDs are still unable to well control spectral stability due to the issues of ion migration and phase separation under external operating conditions. Herein, a strategy using organometallic ligands is reported to achieve spectrally stable PeLEDs. The obtained perovskite film exhibits stable photoluminescence spectra under UV excitation (365nm) and continuous heating of 70 °C. The device delivers an external quantum efficiency (EQE) of 6.7% with 50% lifetime ( T 50 ) of 21.6 min. Under high driving voltage (from 2 to 7.5 V), no obvious spectral shift has occurred for the electroluminescence spectrum at 481 nm. This work confirms the positive effect of organometallic ligands in quasi‐2D perovskite and provides a new idea for proposing effective ligands to act on the perovskite luminescence layer in the future.
Transparent p-type nickel oxide (NiO) thin films have been epitaxially grown on (0001) Al2O3 substrates by a chemical solution method of polymer-assisted deposition for the first time. The films have a high optical transparency of above 95% in the wavelength range of 350-900 nm.
Perovskite solar cell performance was improved significantly by introducing 4,7-Diphenyl-1,10-phenanthroline (Bphen) doped with bis(2-methyldibenzo-[f,h]quinoxaline) (Ir(MDQ)2(acac)) to modify the interface between perovskite (CH3NH3PbI3−xClx)/PCBM (phenyl-C61-butyric acid methyl ester) and an Ag electrode.
4,7-Diphenyl-1,10-phenanthroline (Bphen) is an efficient electron transport and hole blocking material in organic photoelectric devices. Here, we report cesium carbonate (Cs2CO3) doped Bphen as cathode interfacial layer in CH3NH3PbI3-xClx based planar perovskite solar cells (PSCs). Investigation finds that introducing Cs2CO3 suppresses the crystallization of Bphen and benefits a smooth interface contact between the perovskite and electrode, resulting in the decrease in carrier recombination and the perovskite degradation. In addition, the matching energy level of Bphen film in the PSCs effectively blocks the holes diffusion to cathode. The resultant power conversion efficiency (PCE) achieves as high as 17.03% in comparison with 12.67% of reference device without doping. Besides, experiments also demonstrate the stability of PSCs have large improvement because the suppressed crystallization of Bphen by doping Cs2CO3 as a superior barrier layer blocks the Ag atom and surrounding moisture access to the vulnerable perovskite layer.
Achieving high-efficiency perovskite solar cells (PSCs) hinges on the precise control of the perovskite film crystallization process, often improved by the inclusion of additives. While dimethyl sulfoxide (DMSO) is traditionally used to manage this process, its removal from the films is problematic. In this work, methyl phenyl sulfoxide (MPSO) was employed instead of DMSO to slow the crystallization rate, as MPSO is more easily removed from the perovskite structure. The electron delocalization associated with the benzene ring in MPSO decreases the electron density around the oxygen atom in the sulfoxide group, thus reducing its interaction with PbI
Molybdenum ditelluride (MoTe2) has attracted ever-growing attention in recent years due to its novel characteristics in spintronics and phase-engineering, and an efficient and convenient method to achieve large-area high-quality film is an essential step toward electronic applications. However, the growth of large-area monolayer MoTe2 is challenging. Here, for the first time, we achieve the growth of a centimeter-sized monoclinic MoTe2 monolayer and manifest the mechanism of immobilized precursor particle driven growth. Microscopic characterizations reveal an obvious trend of immobilized precursor particles being consumed by the monolayer and continuing to provide a source for the growth of the monolayer. Time-of-flight secondary ion mass spectrometry verifies the attachment of hydroxide ions on the surface of the MoTe2 monolayer, thereby realizing the inhibition of crystal growth along the [001] zone axis and the continuous growth of the MoTe2 monolayer. The first-principles DFT calculations prove the mechanism of immobilized precursor particles and the absorption of hydroxide ions on the MoTe2 monolayer. The as-grown MoTe2 monolayer exhibits a surface roughness of 0.19 nm and average conductivity of 1.5 × 10–5 S/m, which prove the smoothness and uniformity of the MoTe2 monolayer. Temperature-dependent electrical measurements together with the transfer characteristic curves further demonstrate the typical semimetallic properties of monoclinic MoTe2. Our research elaborates the microscopic process of immobilized precursor particles to grow large-area MoTe2 monolayer and provides a new thinking about the growth of many other two-dimensional materials.
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