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Influence of size and localized defect states on photogenerated carrier recombination dynamics, which affects the performance of graphene quantum dots (GQDs) based Si-compatible near-UV heterojunct...

BiVO4 has emerged as a promising photoanode for water oxidation. Technical barriers such as charge recombination and photocorrosion prevent its practical application. In the present work, a NiCo2O4...

Influence of annealing temperature on the properties of In2Ga2ZnO7 (IGZO) thin film prepared using sol–gel method was extensively studied. Annealing treatment at four different temperatures (300, 500, 700 and 900 °C) has transformed the amorphous IGZO to polycrystalline IGZO. The increase in annealing temperature to 900 °C encouraged the formation of interfacial layer on the underlying Si substrate. As a result, a decrement in film current conductivity was perceived and the sample annealed at 900 °C was determined as the closest to having insulating properties. More characterization regarding the structural, morphological and optical characteristics of the annealed films was discussed in this study.

Cu(In,Ga)(S,Se)2 (CIGSe, CIGSSe) has emerged as an attractive thin-film solar cell absorber material owing to its high light absorption coefficient and tunable bandgap. In CIGSSe processing and fab...

Multifunctional lanthanide-doped upconversion nanoparticles (UCNPs) have spread their wings in the fields of flexible optoelectronics and biomedical applications. One of the ongoing challenges lies in achieving UCNP-based nanocomposites, which enable a continuous-wave (CW) laser action at ultralow thresholds. Here, gold sandwich UCNP nanocomposites [gold (Au

An organic conductive polymer, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), is an attractive candidate for a low-cost, low-temperature, and solution-processed electrode material for achieving high-performance flexible and stretchable thin-film devices. Unlike most organic materials, this water-soluble conjugated polymer is highly stable against chemical and physical exposure. It exhibits the most superior mechanical flexibility and the highest optical transparency and electrical conductivity among all organic conductors. Therefore, this conductive polymer is among the most promising alternatives to the expensive, rigid, and brittle metal oxide- and even metal-based electrode materials, such as indium tin oxide (ITO) and gold, in the future solution-processed electronic devices. Nevertheless, the intrinsic conductivity of PEDOT:PSS is typically below 1 S cm−1, which is too low for such devices. Fortunately, the material properties of PEDOT:PSS, including its conductivity, are easily tuned by employing a large number of simple approaches. In this paper, the reports on the successful application of PEDOT:PSS to a wide range of solution-processed organic devices, such as organic light-emitting diodes (OLEDs), organic thin-film transistors (OTFTs), and organic photovoltaics (OPVs), are reviewed. The recent progress in the development of highly conductive PEDOT:PSS-based films for electrode applications in the field of organic electronics is the main focus of the discussion herein.

Perovskite solar cells (PSCs) have emerged as one of the most promising candidates for photovoltaic applications. Low-cost, low-temperature solution processes including coating and printing techniques makes PSCs promising for the greatly potential commercialization due to the scalability and compatibility with large-scale, roll-to-roll manufacturing processes. In this review, we focus on the solution deposition of charge transport layers and perovskite absorption layer in both mesoporous and planar structural PSC devices. Furthermore, the most recent design strategies via solution deposition are presented as well, which have been explored to enlarge the active area, enhance the crystallization and passivate the defects, leading to the performance improvement of PSC devices.

The formation of semiconductor heterostructures is an effective approach to achieve high performance in electrical gas sensing. However, such heterostructures are usually prepared via multi-step procedures. In this contribution, by taking advantage of the crystal phase-dependent electronic property of SnSex based materials, we report a one-step colloid method for the preparation of SnSe(x%)/SnSe2 (100-x%) p-n heterostructures, with x ≈30, 50, and 70. The obtained materials with solution processability were successfully fabricated into NO2 sensors. Among them, the SnSe(50 %)/SnSe2 (50 %) based sensor with an active layer thickness of 2 μm exhibited the highest sensitivity to NO2 (30 % at 0.1 ppm) with a limit of detection (LOD) down to 69 ppb at room temperature (25 °C). This was mainly attributed to the formation of p-n junctions that allowed for gas-induced modification of the junction barriers. Under 405 nm laser illumination, the sensor performance was further enhanced, exhibiting a 3.5 times increased response toward 0.1 ppm NO2 , along with a recovery time of 4.6 min.

Solution-processed ZnO nanoparticle thin film is widely used as the electron transport layers (ETLs) in quantum dot light emitting diodes (QLEDs). While the ZnO nanoparticles (NPs) synthesis proces...

Benefiting from their extraordinary physical properties, methylammonium lead halide perovskites (PVKs) have attracted significant attention in optoelectronics. However, the PVK-based devices suffer from low carrier mobility and high operation voltage. Here, we utilize sorted semiconducting single-walled carbon nanotubes (95% s-SWCNTs) to enhance the performance of thin-film transistors (TFTs) based on the mixed-cation perovskite (MA

Since graphene was first reported as a saturable absorber to achieve ultrafast pulses in fiber lasers, many other two-dimensional (2D) materials, such as topological insulators, transition metal dichalcogenides, black phosphorus, and MXenes, have been widely investigated in fiber lasers due to their broadband operation, ultrafast recovery time, and controllable modulation depth. Recently, solution-processing methods for the fabrication of 2D materials have attracted considerable interest due to their advantages of low cost, easy fabrication, and scalability. Here, we review the various solution-processed methods for the preparation of different 2D materials. Then, the applications and performance of solution-processing-based 2D materials in fiber lasers are discussed. Finally, a perspective of the solution-processed methods and 2D material-based saturable absorbers are presented.

Photon capturing is an essential step for the operation of a solar cell. In this article, we develop a bifacial solar cell with characteristics of double-side photon collection, transparent appearance, mechanical flexibility, and facile processing. The whole device was fully fabricated by a spin-coating technique. A power conversion efficiency (PCE) as high as 2.46% has been achieved using the most prominent photoactive material, poly(3-hexylthiophene):(6, 6)-phenyl C61 butyric acid methyl ester (P3HT:PCBM). The bifacial solar cell can retain 92% of its original PCE after 350 cyclic bending cycles at bending radii of 7.4 mm. In addition to the mechanical instability of the device, photochemical degradation is partially involved in the device operation. We believe that our device with its promising mechanical, physical, and processing features can serve as an essential power element to be integrated with other technologies for the next-generation self-powered technology.

There is growing interest in the development of “green” electronics fabricated from “natural” materials, which could lead to renewable, sustainable, and potentially inexpensive organic optoelectron...

The two-step solution-based process has demonstrated substantial success in fabricating high-efficiency perovskite solar cells in recent years. Despite the high performance, the underlying mechanisms that govern the formation of perovskite films and corresponding device performance are yet to be fully understood. Particularly, organic cation composition used in the two-step solution processing of mixed-cation lead halide perovskite solar cells plays a critical role in the perovskite film formation and the resultant device performance. However, little is understood about the impacts of organic cation composition on the current density-voltage (

Optically induced meta-stable states in the semiconductor lattice temporarily change the conductivity which leads to a phenomenon called persistent photo-conductivity (PPC). We report a PPC effect with long retention time of more than 90 h in solution-processed highly transparent CuO thin film. A 254 nm wavelength light source was used to `set' and thermal annealing at 50°C for 10 minutes and NIR illumination was used to reset PPC effect. Activated trap states without any stimulus which are responsible for PPC effect in CuO thin film has, been investigated by performing temperature-dependent I-V characterization. These trapped charges are released either on heating or illumination with NIR light source. Such a long-enduring PPC achieved in low-cost transparent CuO thin film could pave the way for further study of the feasibility of optically defined, transparent electronics.

Brain-inspired neuromorphic computing is a revolutionary technology to create an intelligent and energy-efficient computing system. However, neuromorphic devices fabricated with complementary metal...

Here we report a solution processed environmentally friendly MoS3 hole-transport material for Sb2Se3 solar cells, where MoS3 exhibits a matched energy level relative to Sb2Se3. In the synthesis, H2S produced by the thermal decomposition of (NH4)2MoS4 is found to efficiently eliminate the antimony oxide impurity formed on the Sb2Se3 surface. Finally, the all-inorganic Sb2Se3 solar cell delivers an efficiency of 6.86% with excellent stability.

Due to their excellent and tailorable optoelectronic performance, low cost, facile fabrication, and compatibility with flexible substrates, solution-processed inorganic and hybrid photo-active materials have attracted extensive interest for next-generation photodetector applications. This review gives a comprehensive compilation of solution-processed photodetectors. The basic structures of the device and important parameters of photodetectors will be firstly summarized. Then the development of various solution processing technologies containing solution synthesis and liquid phase film-forming processes for the preparation of semiconductor films is described. From the materials science point of view, we give a comprehensive overview about the current status of solution processed semiconductor materials including inorganic and hybrid photo-active materials for the application of photodetectors. Moreover, challenges and future trends in the field of solution-processed photodetectors are proposed.

Robust luminogens with thermally activated delayed fluorescence (TADF) and aggregation-induced emission (AIE) characteristics are desirable for high efficiency, low efficiency roll-off and low-cost organic light-emitting diodes (OLEDs). Derived from the 2,4,5,6-tetra(carbazol-9-yl)-1,3-dicyanobenzene (4CzIPN) framework, two TADF-characterized luminogens, 4CzIPN-MO and 4CzPhIPN-MO, are presented in this paper. Encouragingly, along with the carbazole fragment modification of 4CzIPN by using methoxy groups, an unexpected AIE behavior can be observed as for 4CzPhIPN-MO with the insertion of phenyl-bridges between the carbazole moieties and the central benzene ring. The advantages of the novel designed 4CzPhIPN-MO structure are found to be capable to reduce the injection barrier, suppress nonradiative decay, and increase the solid-state photoluminescence (PL) efficiency. Consequently, the nondoped OLED performs outstandingly with a maximum EQE of 14.5%, and extremely low efficiency roll-off of 3.8% and 3.9%, respectively, at a luminance of 100 and 1000 cd m−2, which is among the best EQE roll-off performance of nondoped solution-processed TADF OLEDs reported so far. This work demonstrates that the manipulation of the molecular topologies is a promising and practical strategy for achieving efficient and stable solution-processed OLEDs.

A critical issue in developing high-performance organic light-emitting transistors (OLETs) is to balance the trade-off between charge transport and light emission in a semiconducting material. Although traditional materials for organic light-emitting diodes (OLEDs) or organic field-effect transistors (OFETs) have shown modest performance in OLET devices, design strategies towards high-performance OLET materials and the crucial structure–performance relationship remain unclear. Our research effort in developing cross-conjugated weak acceptor-weak donor copolymers for luminescent properties lead us to an unintentional discovery that these copolymers form coiled foldamers with intramolecular H-aggregation, leading to their exceptional OLET properties. An impressive external quantum efficiency (EQE) of 6.9% in solution-processed multi-layer OLET devices was achieved., Coiled foldamers with intramolecular H-aggregation in semi-ladder copolymers lead towards the highest EQE of 6.9% in solution-processed multi-layer OLETs.

Performance improved solution-processed blue phosphorescent organic light emitting diodes (PhOLEDs) are demonstrated by adopting a double electron transport layer (ETL) strategy, which consists of TPBi and an additional Alq3 ETL. With the help of Alq3 ETL, the performance of the optimal device with a double ETL is significantly enhanced. The maximum luminance of OLEDs is improved from 6787 cd m−2 to 13 054 cd m−2, and the maximum current efficiency is increased from 3.9 cd A−1 to 11.4 cd A−1. Furthermore, the difference of carrier injection in the two types of PhOLEDs is explored by using the transient electroluminescence measurement method. The results imply that double ETL can help to balance electron injection and carrier transport, reduce the interface charge accumulation, leading to a high efficiency. The PL decay of the emission layer with different ETL is detected to analyze the effect of the introduced second ETL layer and the interface on the exciton decay of the emission layer. The results show that the introduced interface in devices with a double ETL has an adverse effect on the exciton emission, which contributes to the serious efficiency roll-off of devices with a double ETL.

High-performance pure near-infrared organic light-emitting materials and devices with full emission over 700 nm are still rare, though urgently needed. Iridium(III) complexes have been proven to be an important class of NIR emitters. Herein, we report a new NIR homoleptic Ir(III) complex, tris[1,4-di(5-n-octylthiophen-2-yl)benzo[g]phthalazine] iridium(III) (Ir(dotbpa)3), with full emission beyond 700 nm with an iridium mass content as low as 10 wt%. Thanks to the introduction of flexible n-octyl groups, Ir(dotbpa)3 shows greatly improved solubility and excellent solution-processability in comparison with its counterpart Ir(dtbpa)3. By utilizing a multifunctional host, solution-processed NIR-OLEDs were fabricated with a simple structure of only three organic layers and they demonstrated a pure NIR emission starting from 725 nm and a peak at 850 nm with the maximum external quantum efficiency of 0.17%, which makes them the first example of pure NIR-OLEDs based on Ir(III) emitters.

Two-dimensional (2D) vdW materials have been integrated into optoelectronic devices to achieve exceptional functionality. However, the integration of large-area 2D thin films into organic light-emitting devices (OLEDs) remains challenging because of the finite number of inorganic 2D materials and the high-temperature requirements of their deposition process. The construction of 2D organometallic materials holds immense potential because of their solution synthesis and unlimited structural and functional diversity. Here, we report a facile route using an oil-water interfacial coordination reaction between organic ligands and divalent metal ions to synthesize crystalline quasi-2D organometallic bis(dithiolato)nickel (NiDT) nanosheets with a centimeter scale and a tunable thickness. The NiDT nanosheets can be directly integrated into OLEDs for use as a hole buffer layer and a fluorescent mounting medium without the aid of a transfer process. Moreover, OLEDs with NiDT nanosheets show not only comparable efficiency to conventional OLEDs but also prolonged device lifetime by nearly 2 times. These results open up a new dimension to use quasi-2D organometallic nanosheets as functional layers in large-area organic devices.

In the present paper, we report the effect of annealing temperature on optical properties of solution processed As2S3 Chalcogenide Glass (ChG) films. Solution processing of ChG films is a low cost, low temperature, scalable route for deposition of high quality films. Annealing of solution processed ChG films is a crucial step for the removal of residual solvent from the films. The optimization of the annealing temperature and corresponding optical properties of ChG films helps in better utilization of these films in functional devices. As2S3 glass was synthesized using melt quenching. The as-prepared As2S3 glass was dissolved in n-butylamine. The solution was then deposited onto glass substrates in the form of thin films. The as-prepared As2S3 glass films were annealed at different temperatures. As-annealed As2S3 glass films were studied using UV-Visible Spectroscopy, Infrared (IR) Spectroscopy, X-ray diffraction (XRD), Raman Spectroscopy and Energy Dispersive X-ray (EDAX) spectroscopy to undestand the effect of annealing on the structural and optical properties of the films

Polarized light sources play a significant role in a growing number of applications: from general illumination to highly efficient displays. Solution-processed polarized light-emitting diodes (pol-LEDs) have attracted remarkable interest because of the wide choice of emissive materials, capability to be solution-processed and easy fabrication. We first classify organic pol-LEDs into two categories according to their aligning techniques, including (1) alignment without an oriented substrate and (2) alignment on an oriented substrate. Recent progress in aligning techniques, emissive materials, substrate materials, device performances and polarizing properties is summarized. We also discuss pol-LEDs based on emissive materials of one-dimensional (1D) II–VI and lead halide perovskite nanomaterials. Finally, an outlook is provided on research trends in the development of solution-processed pol-LEDs.

The ternary blending strategy of introducing a third component into binary organic solar cells (BOSCs) is a feasible and efficient strategy to optimize the performance of BOSCs. Ternary organic solar cells (TOSCs) have an adjustable absorption band for matching the solar light characteristics, easily adjustable photoelectric performance and tunable micro-morphology; therefore, they have become a hotspot in the field of OSC research. Currently, the power conversion efficiency (PCE) of TOSCs has been boosted over 17%. Herein, we give a review on the four possible working mechanisms of TOSCs, roles of the third component in TOSCs, recent progress made in different kinds of active layer materials of TOSCs based on solution-processed non-fullerene acceptors (NFAs), and recent advances in large-area TOSCs and their long-term stability. This review can provide some guidance for the further development of TOSCs. Finally, to help researchers understand the future of TOSCs, the challenges and prospects of TOSCs based on solution-processible NFAs have been provided.

To cut cost and improve efficiency, an interface exciplex system of N,N′-di(naphth-1-yl)-N,N′-diphenyl-benzidine (NPB)/1,3,5-tris[N-(phenyl)benzimidazole]-benzene (TPBi) was employed as a host in solution-processed red phosphorescent organic light-emitting diodes (PhOLEDs). The optimal red PhOLEDs based on the interfacial exciplex host (IEH) present excellent performance with a maximum power efficiency (PEmax) of 40.4 lm W−1, a maximum external quantum efficiency (EQEmax) of 17.2%, and a pretty low turn-on voltage of 2.6 V. Through ideality factor (η) measurements, the results indicate that Langevin recombination (LR) is the dominant carrier recombination pathway in the devices. And the detailed analysis of carrier recombination pathways reveals the advantages of the IEH in carrier transport and recombination. Our work highlights the working process of the IEH and provides evidence for the superiority of the IEH in high performance PhOLEDs.

A series of phenanthroline functionalized triarylamines (TAA) has been designed and synthesised to evaluate their OFET characteristics. Solution processed OFET devices have exhibited p-channel/ambipolar behaviour with respect to the substituents, in particular methoxyphenyl substitution resulted with highest mobility (μh) up to 1.1 cm2 V−1 s−1 with good Ion/off (106) ratio. These compounds can be potentially utilized for the fabrication of electronic devices.

Over the past decade, intensive research efforts have been directed toward the field of organic–inorganic hybrid perovskites, with dramatic progress made in both the photovoltaic performance and device stability. Therefore, it has become the fastest growing photovoltaic research area. Perovskite materials use low-cost earth-abundant elements and can be solution-processed; furthermore, the technology is compatible with large-scale roll-to-roll manufacturing. Recently, the successful demonstration of the photovoltaic performance of perovskites reaching that of the commercialized monosilicon photovoltaic technology combined with the significantly improved stability has made scaling-up the perovskite PV technology to become a new research area, which is the topic of this review. First, the fundamental background knowledge of classical nucleation and crystal growth from a solution is summarized along with its application in perovskite film evolution. We then discuss the common perovskite PV device architectures and perovskite layer deposition methods, followed by summarizing scalable solution approaches with recent progress and related challenges for the scaling-up process. Upon the introduction of the current in-depth understanding of perovskite nucleation and crystal growth, external strategies (including both physical and chemical approaches) controlling the perovskite film formation are reviewed in diverse scalable manufacturing methods. Overall, aiming at overcoming the challenges of transferring from laboratory research, we provide an overview of achieving high-performance perovskite solar cells by using scalable fabrication methods via precise nucleation and crystal growth control during the perovskite film formation process.

All solution-processed semi-transparent perovskite solar cells (PSCs) with high efficiency were fabricated with Ag nanowire (AgNW) top electrode directly coated on the organic electron transport layer (ETL). A unique AgNW/ETL interface morphology was attained by the fabrication of the AgNW-C60 composite electrode through a sequential spin-coating method. The C60 filler spin-coated on the AgNW network engendered a high contact area and favourable energy level alignment at the interface between the ETL and AgNW. As a result, devices based on AgNW-C60 electrode far outperformed devices with pristine AgNW electrodes. By adjusting the thickness of the AgNW film, the AgNW-C60 devices attained a PCE of 11.02%. The incorporation of C60 into the AgNW electrode also led to remarkable stability improvement. The low-temperature solution-processed and semi-transparent AgNW-C60 top electrode is also applicable to other PSC structures with various interfacial layers, thus showing a promising path towards fully-printable, flexible and translucent photovoltaic devices.

The effects of hydrogen peroxide (H2O2) on the device properties and stabilities of solution-processed AlOx metal-oxide-semiconductor capacitors (MOSCAPs) were investigated. It is demonstrate. d that H2O2 is a strong oxidizer to decompose precursor residuals, reduce oxygen vacancy (Vo) and defects density of solution-processed AlOx thin films. The interface quality and the bias-stress (BS) stability of AlOx MOSCAPs were improved by employing H2O2. Furthermore, through carrying out on-site measurements, 7.5 M H2O2 AlOx MOSCAPs exhibited ignorable radiation-induced oxide traps and interface traps under biased-radiation-stress (BRS) with a total dose up to 42 Gy (SiO2). The 7.5 M H2O2 AlOx MOSCAPs also demonstrate the ability to recover under radiation after the bias was interrupted. The reduced number of Vo and high AlOx concentration of 7.5 M H2O2 AlOx could suppress the radiation-induced trapping/de-trapping behavior among the AlOx bulk and the breaking of Si–H bonds at the AlOx/Si interface. Besides, through biased-illumination-stress (BIS) measurements, the breaking of Si–H bonds under negative biased-radiation-stress (NBRS) was further proved. The results demonstrate that employing H2O2 in the solution-process is simple and effective; it has significant potential to improve the stabilities of large-area electronics for nuclear and aerospace applications.

To scale up production of perovskite photovoltaics, state-of-the-art laboratory recipes and processes must be transferred to large-area coating and drying systems. The development of in situ monitoring methods that provide real-time feedback for process control is pivotal to overcome this challenge. Herein, correlative in situ multichannel imaging (IMI) obtaining reflectance, photoluminescence intensity, and central photoluminescence emission wavelength images on areas larger than 100 cm2 with subsecond temporal resolution using a simple, cost-effective setup is demonstrated. Installed on top of a drying channel with controllable laminar air flow and substrate temperature, IMI is shown to consistently monitor solution film drying, perovskite nucleation, and perovskite crystallization. If the processing parameters differ, IMI reveals characteristic changes in large-area perovskite formation dynamics already before the final annealing step. Moreover, when IMI is used to study >130 blade-coated devices processed at the same parameters, about 90% of low-performing devices contain coating inhomogeneities detected by IMI. The results demonstrate that IMI should be of value for real-time 2D monitoring and feedback control in industrial-scale, high-throughput fabrication such as roll-to-roll printing.

Al/TE (top electrode)/AlOx/Pt RRAM (resistive random access memory) devices with solution-processed spin-coated AlOx layers annealed at various temperatures (225/250/275 °C) exhibited typical bipolar resistive switching performance with low SET/RESET voltage ( 103) and excellent stability (retention time over 104 s and endurance cycles more than 100). Ni and TiN were chosen as the TE, respectively. Better RS characteristics were obtained on Ni/AlOx/Pt RRAM devices with lower operating voltage and better stability. In addition, the voltage variation between Ni/AlOx/Pt and TiN/AlOx/Pt RRAM devices was investigated. Compared with Ni/AlOx/Pt RRAM devices, TiN/AlOx/Pt devices operated with higher operation voltage at various annealing temperatures, which indicated the influence of work function difference (△ΦM) between TE and BE (bottom electrode). The greater the △ΦM, the more energy consumption and the higher operation voltage were demanded.

Chalcogenides-based thin film solar cells are great competitors to beat high efficiencies as silicone solar cells. The chalcogenides that have been commonly used as absorber materials are CIS, CIGS, and CZTS. They present some advantages of having a direct and tunable band gap, high absorption coefficient and respectable efficiency to cost ratio. Solution processable deposition approaches for the fabrication of solar cells attracts a great deal attention due to its lower capital cost of the manufacturing than the vacuum-based techniques. In this chapter, we detail the use of a low-cost method of deposition for the chalcogenide thin films by spin-coating and spray-coating, which is already widely employed in several fields of industries.

In this work, we presented experimental observation on solution-processed bulk heterojunction organic photodiode using vanadyl 2,11,20,29-tetra tert-butyl 2,3 naphthalocyanine (VTTBNc) as a p-type material. VTTBNc is blended with two different acceptors, which are PC61BM and PC71BM, to offer further understanding in evaluating the performance in organic photodiode (OPD). The blend film of VTTBNc:PC71BM with a volumetric ratio of 1:1 exhibits optimized performance in the VTTBNc blend structure with 2.31 × 109 Jones detectivity and 26.11 mA/W responsivity at a −1 V bias. The response and recovery time of VTTBNc:PC71BM were recorded as 241 ms and 310 ms, respectively. The light absorption measurement demonstrated that VTTBNc could extend the light absorption to the near-infrared (NIR) region. The detail of the enhancement of the performance by adding VTTBNc to the blend was further explained in the discussion section.