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Introduction

Recently, metal halide perovskites have been hailed by many as the “wonder” semiconductor for photovoltaics, because of their outstanding optoelectronic properties and facile solution processability. Perovskite-based solar cells have reached a power conversion efficiency record above 25% in just more than a decade of research. Halide perovskite semiconductors constitute a wide family of materials

Isoindigo-based aza-BODIPY small molecule for N-type organic field-effect transistors

To date, most of the reported conjugated materials are p-type semiconductors, while the advances in n-type or ambipolar conjugated materials greatly fall behind those in p-type counterparts. Well-defined n-type semiconductors should possess suitable electron-deficient groups and relatively low lowest unoccupied molecular orbitals (LUMO) levels that facilitate the electron injection and stabilize t

Hydrogen-Bonded Dopant-Free Hole Transport Material Enables Efficient and Stable Inverted Perovskite Solar Cells

Although many dopant-free hole transport materials (HTMs) for perovskite solar cells (PSCs) have been investigated in the literature, novel and useful molecular designs for high-performance HTMs are still needed. In this work, a hydrogen-bonding association system (NH···CO) between amide and carbonyl is introduced into the pure HTM layer. Our study demonstrates that the hydrogen-bonding associatio

Photo-Induced Charge Carrier Dynamics of Metal Halide Perovskite

Currently, a high efficiency single layer metal halide perovskite solar cell employs a TiO2 mesoporous layer as an electron transporting material and spiro-OMeTAD as a hole transporting material. The efficient charge carrier separation and retarded interfacial charge recombination are expected to achieve a high solar to energy conversion efficiency. In this presentation, we will demonstrate how st

Hydrogen bonding drives the self-assembling of carbazole-based hole-transport material for enhanced efficiency and stability of perovskite solar cells

Designing a hole-transport material (HTM) that guarantees effective hole transport while self-assembling at the perovskite|HTM interface with the formation of an ordered interlayer, has recently emerged as a promising strategy for high-performance and stable perovskite solar cells (PSCs). Hydrogen bonding (HB) is a versatile multi-functional tool for the design of small molecular HTMs. However, to

Side-chain engineering by thymine groups enables hydrogen bond in P-type donor-acceptor polymers with enhanced optoelectronic properties

Realizing ordered structures at the molecular level is a key approach to increase the charge mobility of organic semiconductors. However, the typical solution-based methods employed for the processing make the achievement of well-organized organic nanostructures difficult with the favored formation of disordered assemblies. To realize well-ordered thin films, one needs to design conjugated materia

Enhancing the Microstructure of Perovskite-Inspired Cu-Ag-Bi-I Absorber for Efficient Indoor Photovoltaics

Lead-free perovskite-inspired materials (PIMs) are gaining attention in optoelectronics due to their low toxicity and inherent air stability. Their wide bandgaps (≈2 eV) make them ideal for indoor light harvesting. However, the investigation of PIMs for indoor photovoltaics (IPVs) is still in its infancy. Herein, the IPV potential of a quaternary PIM, Cu2AgBiI6 (CABI), is demonstrated upon control

Flexible Organic Photovoltaics with Star-Shaped Nonfullerene Acceptors End Capped with Indene Malononitrile and Barbiturate Derivatives

The design and synthesis of three star-shaped nonfullerene (NFA) acceptors, TPA-2T-INCN, TPA-2T-BAB, and TPA-T-INCN, based on a triphenylamine (TPA) core and linked through π-conjugated thiophene (T) spacers to different terminal units (3-oxo-2,3-dihydro-1H-inden-1-ylidene) malononitrile, INCN, and 1,3-dimethylbarbituric acid, BAB), are reported. These materials are blended with the widely used po

Beyond hydrophobicity : how F4-TCNQ doping of the hole transport material improves stability of mesoporous triple-cation perovskite solar cells

Despite the outstanding power conversion efficiency of triple-cation perovskite solar cells (PSCs), their low long-term stability in the air is still a major bottleneck for practical applications. The hygroscopic dopants traditionally used in hole transport materials (HTMs) severely degrade the perovskite film. The p-type F4-TCNQ doping of the well-known spiro-OMeTAD HTM enables hydrophobicity-ind

From Transistors to Phototransistors by Tailoring the Polymer Stacking

It is universally acknowledged that highly photosensitive transistors are strongly dependent on the high carrier mobility of polymer-based semiconductors. However, the polymer π–π stacking and aggregation, required to increase the charge mobility, conversely inhibit the dissociation of photogenerated charge carriers, in turn accelerating the geminate recombination of electron-hole pairs. To explor

Moisture-Assisted near-UV Emission Enhancement of Lead-Free Cs4CuIn2Cl12 Double Perovskite Nanocrystals

Lead-based halide perovskite nanocrystals (NCs) are recognized as emerging emissive materials with superior photoluminescence (PL) properties. However, the toxicity of lead and the swift chemical decomposition under atmospheric moisture severely hinder their commercialization process. Herein, we report the first colloidal synthesis of lead-free Cs4CuIn2Cl12 layered double perovskite NCs via a faci

Efficiency improvement for perovskite-inspired Cs3Sb2I9solar cells using P3HT as the hole transport material

In this work, we introduce P3HT (poly(3-hexylthiophene-2,5-diyl)) as an efficient hole transport material (HTM) for lead-free Cs3Sb2I9perovskite-inspired solar cells. The P3HT doubles the power conversion efficiency (PCE) of the solar cells (PCE = 2.5% for the champion device) by improving all of the figures of merit: the fill factor, open-circuit voltage, and the short-circuit current. The maximu

Photoinduced Charge Carrier Dynamics of Metal Chalcogenide Semiconductor Quantum Dot Sensitized TiO2 Film for Photovoltaic Application

Semiconductor quantum dot (QD) sensitization is one of the most attractive structures to employ QDs for photovoltaic application. The function of QD sensitized solar cells (QDSSC) is controlled by the interfacial charge transfer dynamics. Here we employ transient absorption spectroscopy (TAS) to assess charge transfer dynamics at CdS QD/TiO2 interface, and correlate their dynamics with their solar

Fast non-ambipolar diffusion of charge carriers and the impact of traps and hot carriers on it in CsMAFA perovskite and GaAs

We performed a comprehensive study of the charge carrier diffusion in the CsMAFA perovskite, one of the state-of-the-art perovskites for photovoltaic applications, starting from the diffusion of hot carriers to the eventual trapping at the surfaces and grain boundaries. We discovered evidence of non-ambipolar diffusion by using ultrafast transient reflectance spectroscopy: by comparing the transie

Sulfonated Dopant-Free Hole-Transport Material Promotes Interfacial Charge Transfer Dynamics for Highly Stable Perovskite Solar Cells

The integration of a functional group into dopant-free hole-transport materials (HTMs) to modify the perovskite|HTM interface has become a promising strategy for high-performance and stable perovskite solar cells (PSCs). In this work, a sulfonated phenothiazine-based HTM is reported, namely TAS, which consists of a butterfly structure with a readily synthesized N,​N-​bis[4-​(methylthio)​phenyl]​an

Octahedral distortion driven by CsPbI3nanocrystal reaction temperature-the effects on phase stability and beyond

Cesium lead iodide (CsPbI3) perovskite nanocrystals (NCs) suffer from a known transformation at room temperature from their red-emitting (black) to non-emitting (yellow) phase, induced by the tilting of PbI6 octahedra. While the reported attempts to stabilize CsPbI3 NCs mainly involve Pb2+-site doping as well as compositional and/or NC surface engineering, the black phase stability in relation onl

Halogen-Bonded Hole-Transport Material Suppresses Charge Recombination and Enhances Stability of Perovskite Solar Cells

Interfaces play a crucial role in determining perovskite solar cells, (PSCs) performance and stability. It is therefore of great importance to constantly work toward improving their design. This study shows the advantages of using a hole-transport material (HTM) that can anchor to the perovskite surface through halogen bonding (XB). A halo-functional HTM (PFI) is compared to a reference HTM (PF),

Two-Dimensional Antimony-Based Perovskite-Inspired Materials for High-Performance Self-Powered Photodetectors

The ongoing Internet of Things revolution has led to strong demand for low-cost, ubiquitous light sensing based on easy-to-fabricate, self-powered photodetectors. While solution-processable lead-halide perovskites have raised significant hopes in this regard, toxicity concerns have prompted the search for safer, lead-free perovskite-inspired materials (PIMs) with similar optoelectronic potential.

Lead-free cesium titanium bromide double perovskite nanocrystals

Double perovskites are a promising family of lead-free materials that not only replace lead but also enable new optoelectronic applications beyond photovoltaics. Recently, a titanium (Ti)-based vacancy-ordered double perovskite, Cs2 TiBr6, has been reported as an example of truly sustainable and earth-abundant perovskite with controversial results in terms of photoluminescence and environmental st

Primary photocatalytic water reduction and oxidation at an anatase TiO2 and Pt-TiO2 nanocrystalline electrode revealed by quantitative transient absorption studies

Quantitative assessments of electron and hole transfer dynamics with water on anatase nanocrystalline TiO2 films were conducted by employing a series of transient absorption spectrometers. For water reduction reactions, both conduction band and trapped electrons decay with two different single exponential components with the difference in time scale of 6∼7 orders of magnitudes. The faster reaction