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Organic-inorganic hybrid lead halide perovskite materials with the general formula MAPbI3-nBrn (n = 0, 1, 2, and 3) exhibiting a range of crystal structures and a wide range of optical bandgaps are explored for their potential to harvest energy from ambient light sources. The replacement of I− with Br− is found to transform the perovskite crystal structure from the tetragonal for MAPbI3 to the pseudo cubic for MAPbI2Br and MAPbIBr2 and cubic for MAPbBr3 while increasing the optical bandgap from 1.59 eV to 2.31 eV. Photovoltaic cells (PVCs) are constructed using these perovskites and are found to exhibit power conversion efficiencies (PCEs) of 29.83 (MAPbI3), 23.75 (MAPbI2Br), 21.47 (MAPbIBr2), and 19.94% (MAPbBr3) under LED light illumination (1000 lux; ~0.371 mW cm−2), with a record high open-circuit voltage (VOC) of 1.15 V being observed for the MAPbBr3. The effect of crystal structure variation on the charge carrier mobility, trap states, recombination losses, photovoltaic properties, and operational stabilities has been investigated systematically under indoor illumination. Overall, this work provides a clear vision on the influence of perovskite crystal structures upon the photovoltaic properties and shows a pathway to achieve high VOC in perovskite PVCs under low-intensity ambient light sources.

Various organic cations (e.g., methylammonium (MA+), butylammonium (BA+), formamidinium (FA+), etc.) have been studied and used in organometallic halide perovskite solar cells (PSCs). Most of the c...

The design and synthesis of a stable and efficient hole-transport material (HTM) for perovskite solar cells (PSCs) are one of the most demanding research areas. At present, 2,2′,7,7′-tetrakis[N,N-d...

As an essential component in efficient perovskite photovoltaics (PPVs), hole transport materials (HTMs) that meet the intricate requirements for next-generation charge transport layers have recently been of immense interest. Specifically, functionally tailored HTMs that aid in mitigating charge transport limitations and interfacial defects and thereby enhance the performance of both indoor and outdoor PPVs are being sought after. Herein, we developed a novel graft-type polymer composed of a benzo[1,2-b:4,5:b′]dithiophene-based main chain and poly(ethylene glycol) (PEG) side chains as an efficient dopant-free HTM for PPVs. Through a systemized tailoring of the contents of the side chains, we were able to control the hole transport and interfacial passivation abilities of the graft-type polymeric HTM. The polymeric HTM with an optimized PEG side chain exhibited a higher hole mobility, a reduced amount of interfacial traps, and an enhanced device stability compared to the control polymeric HTM. The PPVs capped with the optimized graft-type polymeric HTM demonstrated remarkably high power conversion efficiencies up to 38.2% and 21.7% under 1000 lux LED and AM 1.5 solar illuminations, respectively.

A Spiro fluorene-based dopant-free hole-transporting material denoted as Spiro-IA has been designed and developed from inexpensive starting materials with high yield via a simple synthetic approach for application in perovskite solar cells (PSCs). The unit cost of Spiro-IA can be as low as 1/9th that of the conventional Spiro-OMeTAD. Moreover, Spiro-IA shows good solubility in different organic solvents, e.g. CHCl3, acetone, EtOH, and DMF, and showed favorable charge-transport ability and greater photocurrent density compared to Spiro-OMeTAD. The UV absorption/emission spectra of Spiro-IA (λmax = 430 nm, Emax = 601 nm) are red shifted compared to those of Spiro-OMeTAD (λmax = 388 nm, Emax = 414 nm) with larger stokes shift values (171 nm) which helps suppress the loss of incident photons absorbed by the HTM and is more beneficial for improving the performance of PSCs. Optical and electrochemical studies show that Spiro-IA fulfilled the basic requirements of the hole transfer and electron regeneration process in the fabricated devices. PSCs fabricated (surface area = 1.02 cm2) with dopant-free Spiro-IA achieved a maximum power conversion efficiency (PCE) of 15.66% (JSC = 22.14 mA cm−2, VOC = 1.042 V, FF = 0.679%), which was comparable to that of the most commonly used Li-doped Spiro-OMeTAD (PCE = 15.93%, JSC = 20.37 mA cm−2, VOC = 1.057 V, FF = 0.74%) and surpassed that of the dopant-free Spiro-OMeTAD (PCE = 9.34%). Additionally, the PSCs based on dopant-free Spiro-IA achieved outstanding long-term stability and favorable conductivity (σ = 2.104 × 10−4 S cm−1) compared to those based on Spiro-OMeTAD (σ = 9.00 × 10−8 S cm−1). DFT studies were performed using Gaussian 09 at the B3LYP/6-31G (d/p) level to investigate their electron cloud delocalization in HOMO/LUMO levels. These results showed that Spiro-IA could be a promising candidate for low-cost PSC technology and has a great chance to supersede the expensive Spiro-OMeTAD.

Conventional, high-efficiency, hybrid organic–inorganic perovskites (e.g., methylammonium lead iodide (MAPbI3) and formamidinium lead iodide (FAPbI3)) having ammonium-based organic cations exhibit poor moisture stability mainly due to the effective hydrogen bonding interaction of nitrogen in the ammonium-based cations with water molecules. Recently, a sulfonium-based cation, trimethylsulfonium (TMS+), has attracted growing attention for the development of moisture-stable hybrid perovskite solar cells (PSCs). This research investigated the photovoltaic performance of trimethylsulfonium lead triiodide (TMSPbI3) based PSCs and their moisture stability both experimentally and theoretically. The results revealed that TMSPbI3 exhibited a relatively large optical band gap (Eg = 2.32 eV) and high absorption coefficient (α = 2.30 × 104 cm−1 at 500 nm) with a hexagonal one-dimensional crystal structure. The PSCs with a device structure of FTO/c-TiO2/m-TiO2/TMSPbI3/CuSCN/Au exhibited a power conversion efficiency (PCE) of 2.22% with no hysteresis in the I–V curve, and high moisture stability at ambient temperature (25 ± 3 °C, ca. 50% relative humidity) with a PCE loss of only ca. 4.6% after 500 h. This result could be attributed to the absence of the hydrogen bonding interaction of TMS+ with water molecules, leading to the effective stabilization of TMSPbI3 compared to MAPbI3 and FAPbI3, verified by density functional theory calculations.

The stability of graphene dispersions in water is of both scientific and technological significance. We studied the dispersion stability of electrochemically exfoliated graphene in an aqueous medium to minimize the strong aggregation tendency, within a short period, of graphene prepared in various electrolytes. This study focused on increasing the dispersion stability of graphene and finding the reason for its poor dispersion stability. The residual electrolyte trapped in the graphene layers was difficult to be removed from electrochemically exfoliated graphite and caused a significant aggregation. The stability and dispersion concentration can be improved by removing the trace amount of aqueous electrolyte. The aggregation mechanism of graphene in aqueous media is proposed and discussed in detail.

Two novel highly conjugated small organic molecules as hole transporting materials (HTMs) coded T(EDOT-TPA)2 and DBT(QT-TPA)2 were designed and developed by utilizing facile synthetic procedures with high yields. The fabricated perovskite solar cells (PSCs) utilizing these HTMs without any dopants under 1 sun illumination (100 mW cm−2, AM 1.5G) and surface area of 1.02 cm2 achieved a short circuit current (JSC = 19.23), open circuit voltage (VOC = 1.042), fill factor (FF = 0.679) and overall power conversion efficiency (PCE = 13.61%) for DBT(QT-TPA)2. While, T(EDOT-TPA)2 exhibited (JSC = 20.25, VOC = 1.04, FF = 0.583, and PCE = 12.27%). These dopant free HTM based PSCs achieved superior PCEs compared to that of undoped Spiro-OMeTAD (PCE = 9.34%) based PSCs and a comparable photovoltaic performance to the PSCs using doped Spiro-OMeTAD (JSC = 20.37, VOC = 1.057, FF = 0.74, and PCE = 15.93) as the HTM under same fabrication conditions. Noticeably, the absence of additives is of significant importance, as DBT(QT-TPA)2 and T(EDOT-TPA)2 based PSCs still produces a Jsc up to 20.25 mA cm−2 and a comparable PCE of 13.61%, which reduces the fabrication cost of cm sized PSCs.

Oxide scales often formed on the surface of stainless steel, and it is of high interest to descale the surface oxide effectively and environment-friendly during steel smelting and engineering processing. It is generally done by treating the oxide layer under strong and harsh mixed acid (HNO3 + HF) conditions or in a strong molten salt (NaOH + NaNO3) environment at high temperatures, while the generation of very harmful and environmentally hazardous gases, such as NO x , is inevitable. A novel, simple, fast, and environment-friendly electrochemical method at ambient temperature is proposed in this research to remove the oxide scale from the stainless steel surface using an ionic liquid with a small amount of HCl. It was found that the optimized electrochemical anodization treatment in an ionic liquid environment could significantly improve the descaling efficiency at least 50 times faster than the simple passive and slow dissolution in a mixture of an ionic liquid and a concentrated acid.

Luminescent solar concentrators (LSCs) provide a transformative approach to integrating photovoltaics into a built environment. In this paper, we report thin-film LSCs composed of intramolecular charge transfer fluorophore (DACT-II) and discuss the effect of two polymers, polymethyl methacrylate (PMMA), and poly (benzyl methacrylate) (PBzMA) on the performance of large-area LSCs. As observed experimentally, DACT-II with the charge-donating diphenylaminocarbazole and charge-accepting triphenyltriazine moieties shows a large Stokes shift and limited re-absorption losses in both polymers. Our results show that thin-film LSC (10 × 10 × 0.3 cm3) with optimized concentration (0.9 wt%) of DACT-II in PBzMA gives better performance than that in the PMMA matrix. In particular, optical conversion efficiency (ηopt) and power-conversion efficiency (ηPCE) of DACT-II/PBzMA LSC are 2.32% and 0.33%, respectively, almost 1.2 times higher than for DACT-II/PMMA LSC.

In this study, we report a new BODIPY-based design, called the cross-conjugated design, that takes advantage of the α- and β-position functionalization of the BODIPY core. After synthesis, and compared to a more standard BODIPY dye, using similar functional groups and based on a horizontal design, called h-BOD, the new cross-conjugated BODIPY dye (cc-BOD) exhibits clearly the highest conjugation and light harvesting properties. Consequently, when used as photosensitizers in dye-sensitized solar cells (DSSCs), an impressive improvement of power conversion efficiency (PCE) has been observed, with a PCE of 6.02% with broad incident photon to current conversion efficiency (IPCE) for cc-BOD, compared to only 3.7% for h-BOD. Moreover, by co-sensitizing a DSSC with the two complementary absorbing dyes h-BOD and cc-BOD, we further improved the PCE up to 6.2%.

A tetrathiafulvalene derivative containing two amide units for intermolecular hydrogen bonds (Bis-amide-TTF) was found to form supramolecular assemblies, in which intermolecular TTF cores were stacked with each other. The electrical conductivity of Bis-amide-TTF-based film was 1.28 × 10 - 5 S c m - 1 , which was greater than that of spiro-OMeTAD doped with t-butylpyridine and bis(trifluoromethane)sulfonimide lithium salt ( 8.37 × 10 - 6 S c m - 1 ). Bis-amide-TTF was applied as a hole transport material (HTM) for perovskite solar cells (PSCs). The Bis-amide-TTF film has a deeper HOMO level than that of spiro-OMeTAD, leading to an increased open-circuit voltage of the PSCs. The power conversion efficiency of 14.5% with a short-circuit current density (Jsc) of 19.8 mA cm−2, an open-circuit voltage (Voc) of 1.11 V, and a fill factor (FF) of 66% was achieved for PSCs fabricated with the dopant-free Bis-amide-TTF-based HTM, which was comparable to that obtained with spiro-OMeTAD with the dopants (15.5%).

The electrochemical exfoliation of graphene is a very useful technique to prepare highly conductive graphene with a low defect level. However, low dispersion stability is a barrier to this process being used to prepare graphene directly in a wide range of applications. Even though the dispersion stability and concentration of graphene are important, the reasons for the lower dispersion stability and lower concentration of electrochemically exfoliated graphene have not yet been clarified. In this study, we identified that the strong electrostatic attractive interaction between charged ions from electrolytes at the interfaces of graphene layers substantially deteriorated the dispersion stability. Both the stability and the concentration of graphene dispersions were substantially enhanced upon removal of the residual electrolytes from the organic solvents used in this study.

Fast dye-regeneration and slow charge recombination are prerequisites for selecting superior redox couples of electrolytes to obtain highly efficient dye-sensitized solar cells (DSSCs). Although the ubiquitous combination of the I−/I3− redox couple demonstrates high power conversion efficiency (PCE), it suffers from several limitations such as a large potential difference of approximately 560 mV between the Fermi level of I−/I3− and the HOMO level of the N719 dye as well as high visible light absorption. These limitations cause inefficient dye-regeneration and significantly enhance the back reaction rate of photoelectrons to I3− in the electrolyte. This review discusses recent progress in the conception and device performance of different binary redox couples in DSSCs based on lowering potential differences, the back reaction of photo-induced electrons, the absorption of visible light, and improvement of dye-regeneration. We specifically focus on recent strategies targeted for effectively increasing both the open circuit voltage of DSSCs up to ˜100 mV and the PCE to above 10%; these strategies include introduction of binary redox couples or additional redox species to conventional iodine-based electrolytes. Moreover, we propose future directions for the further development of binary redox couples with advanced concepts for achieving DSSCs with high performance and high stability.

Organometallic halide perovskite materials have promising photovoltaic properties and emerged as a cost-effective solar cell technology. However, a synthesis protocol to fabricate high-quality pero...

For developing low-temperature processed electron-transporting layer in perovskite solar cells, titanium oxide (TiO2) nanoparticle was synthesized through the non-hydrolytic sol-gel route. TiO2 nanoparticles showed uniform film coverage, high transparency in the visible region with wide optical bandgap, and high electrical conductivity after systematically optimizing the synthetic reaction time, the thermal annealing temperature, and the concentration of Nb doping. When TiO2 nanoparticle was introduced as an electron-transporting layer through low-temperature deposition process, the perovskite solar cells fabricated in ambient conditions showed high efficiencies of 18.97% and 13.51% on the rigid glass and the flexible plastic substrate, respectively. An impressively high open circuit voltage of 1.17 V and short circuit current density of 22.21 mA cm−2 were achieved due to the well aligned work function and better electrical conductivity of Nb-doped LT-TiO2 layer. Importantly, solar cells fabricated with TiO2 nanoparticle showed high thermal stability, negligible hysteresis, and reduced charge recombination loss at electron-transporting layer/perovskite interfaces. This study shows that TiO2 nanoparticle can be obtained through the low cost and facile synthesis and has high potential as an electron-transporting layer for low-temperature processable perovskite solar cells.

Announced as one of the top 10 research breakthroughs in 2016, perovskite solar cells (PSC) have advanced rapidly as an established photovoltaic technology. The power conversion efficiency (PCE) of PSCs has increased quickly from 3.8% to 23.7% within a period of just 7 years. This very high PCE has been achieved by using perovskite compounds with lead (Pb) as the divalent metal ion. However, for further scale-up and commercialization, the toxicity of Pb has been identified as one of the key drawbacks for this technology. Numerous avenues for development of lead-free low-toxicity perovskite absorbers have been pursued. The unclear effect of using low-toxicity materials on optimal performance with suitable characteristics has motivated the writing of this review. Results from low-toxicity perovskite solar cells utilizing partial or complete substitution of the Pb2+ cation as the absorber layer are discussed in detail. Moreover, we discuss the limitations of low-toxicity absorber materials. This review summarizes the key points of film quality control, degradation effect, Pb replacement suitability, and photovoltaic performance of reported low toxicity alternate perovskite absorbers for PSCs.

Recently, while increasing research has been focused toward improving the efficiency of various photovoltaic devices under low light intensities, few studies have reported on multi-donor-, multi-acceptor-based bulk heterojunctions (BHJ). In this study, we have demonstrated the utilization of a quaternary BHJ for indoor light energy harvesting applications. We utilized a PCDTBT:PTB7:PC61BM:PC71BM-based BHJ structure in order to improve the morphology, absorption window, and the charge transport properties of the photovoltaic device. The ability of ternary photovoltaics to attain high power-conversion efficiency (PCE) by improving the morphology and the charge transport properties had already been validated in another study. We show that the advantages of a stable quaternary solar cell can also be achieved with an optimized BHJ composition ratio of 5:5:3:12, which provides a PCE of 10.6%. Our device showed high shunt resistance and low series resistance, thus facilitating appreciable charge extraction even under low-intensity light conditions such as 500 lx white LED illumination.

An in-depth study on the photovoltaic characteristics under indoor lights, i.e., light-emitting diode (LED), fluorescent lamps, and halogen lamps, was performed with varying the photoactive layer thickness (120–870 nm), by comparing those under 1-sun condition. The semi-crystalline mid-gap photoactive polymer, poly[(2,5-bis(2-hexyldecyloxy)phenylene)-alt-(5,6-difluoro-4,7-di(thiophen-2-yl)benzo[c][1,2,5]thiadiazole)] (PPDT2FBT) and a fullerene derivative, [6,6]-phenyl C71 butyric acid methyl ester (PC70BM) were used as a photoactive layer. In the contrary to the measurements under 1-sun condition, the indoor devices show a clearly different behavior, showing the thickness tolerant short-circuit current density (JSC) and fill factor (FF) values with 280–870 nm thick photoactive layers. The retained JSC and FF values of thick indoor devices were discussed in terms of the parasitic resistance effects based on the single-diode equivalent circuit model. The much lower series/shunt resistance (Rs/RP) ratio was measured with thick photoactive layer (≥280 nm), resulting in negligible decreases in the JSC and FF values even with a 870-nm-thick active layer under the LED condition. Under 1000 lx LED light, the PPDT2FBT:PC70BM device showed an optimum power conversion efficiency (PCE) of 16% (max power density, 44.8 μW/cm2) with an open-circuit voltage of 587 mV, a JSC of 117 μA/cm2, and a FF of 65.2. The device with a 870-nm-thick active layer still exhibited an excellent performance with a PCE of 12.5%. These results clearly suggest that the critical parasitic resistance effects on the performance vary depending on the light illumination condition, and the large RP associated with the viable thick photoactive layer and the well-matched absorption (of photoactive layer) with the irradiance spectrum (of indoor light) are essential to realize efficient indoor photovoltaic cells with high JSC and FF.

In this work, a simple and one-step solvothermal method has been developed for directly growing three-dimensional flower-like cobalt sulfide (CoS) on the fluorine-doped tin oxide coated glass substrate (FTO) for the counter electrode in the dye sensitized solar cell. The electroctalytic activity of the CoS@FTO towards the I3− to I− reduction exhibited almost similar electrocatalytic properties to the Pt-based counter electrode. The dye-sensitized solar cell (DSSC) assembled with CoS@FTO counter electrode attained almost similar photovoltaic performance (5.64%) to that of the DSSC with Pt@FTO counter electrode (5.9%) under 1 sun illumination. The adhesion stability of the CoS deposited at FTO was also studied using strong adhesive tape test, and the results show that after the strong adhesive tape test, the CoS@FTO retained almost 95% of the coating. The similar and comparative performance of the CoS@FTO to the Pt@FTO may be due to the high surface area originating from the 3D flower-like morphology, and the excellent electrocatalytic activity of the CoS.

We have synthesized cobalt-doped NiOx nanoparticles containing 0.5, 1, 2, 5 and 10 mol% cobalt ions and have investigated their electronic properties, which can be processed into smooth and pinhole-free layers at low temperature (

Edge-carboxylated graphene nanoplatelets (ECG), prepared by a mechano-chemical reaction (or ball milling method) in the presence of dry ice, are eligible for an efficient electrode materials for electrochemical supercapacitors. ECG contained a higher content of edge-carboxylic groups with less structural defects, compared with the nitrogen-doped carboxylic graphene (NGOOH) prepared from the conventional solution-exfoliation of graphite. The structural defects level of ECG is ca. 16.2%, while it was ca. 48.9% for NGOOH. The edge-carboxylation increases the electroactive surface area, hydrophilicity and wettability of graphene without serious deterioration of the intrinsic properties e.g., chemical, mechanical and electronic properties. In result, it is more effective in enabling ion adsorption and rapid electrolyte diffusion within the pores of graphene which results in a significant increase of specific capacitance (Csp) to 365.72 F/g at a current density of 1 A/g, with a good charge–discharge property and rate capability for ECG. On the other hand, the Csp significantly decreases to ca. 175.05 F/g for NGOOH, as its high level of structural defects seriously affected its electronic properties.

A novel electrochemical aptasensor based on gold nanoparticles decorated on boron nitride nanosheets (AuNPs/BNNSs) for the sensitive and selective detection of myoglobin (Mb) is reported. BNNSs were chemically synthesized by a low-cost and simple hydrothermal method. They were deposited onto the fluorine-doped tin oxide (FTO) electrode by a spin-coating method. Subsequently, AuNPs were chemically deposited onto the BNNS/FTO electrode by a seed-mediated chemical reduction method, with an average particle size of approximately 10 nm. The AuNPs/BNNSs/FTO electrode was used as a transducer to immobilize a thiol-functionalized DNA aptamer (Apt) via the covalent interaction of Au–S for the specific binding of Mb. [Fe(CN)6]3-/4- was used as a redox probe to monitor the oxidation current variation upon the binding of Mb with varying concentrations onto the sensor surface. The Apt/AuNPs/BNNSs/FTO sensor shows a high signal response for Mb with a detection limit of 34.6 ng/mL and a dynamic response range of 0.1–100 µg/mL. It is a promising candidate for point-of-care diagnosis in real samples. This strategy could make possible the application of other 2D materials with wide bandgaps for the development of biosensors.

The steric shielding offered by sensitizers on semiconducting surfaces as a result of branching in the dyes used offers the less utilization of semiconducting substrate sites during device fabrication in dye-sensitized solar cells (DSSCs). This work proposes a strategy to increase the coverage through the utilization of small molecules which have the ability to penetrate into the sites. The small molecules play the dual role of vacancy filling and sensitization, which can be viewed as an alternative to co-sensitization also. Hence, we show for the first time ever that the co-adsorption of catechol with Z907 as a sensitizer enhances the electron density in the photo-anode by adsorbing on the vacant sites. Catechol was subsequently adsorbed on TiO2 after Z907 as it has a stronger interaction with TiO2 owing to its favorable thermodynamics. The reduced number of vacant sites, suppressed charge recombination, and enhanced spectral response are responsible for the improvement in the PCEs. Quantitatively, both organic and aqueous electrolytes were used and the co-sensitized DSSCs had PCE enhancements of 7.2 and 60%, respectively, compared to the control devices.

Temperature is a fundamental physical quantity whose accurate measurement is of critical importance in virtually every area of science, engineering, and biomedicine. Temperature can be measured in many ways. In this pedagogically focused review, we briefly discuss various standard contact thermometry measurement techniques. We introduce and touch upon the necessity of non-contact thermometry, particularly for systems in extreme environments and/or in rapid motion, and how luminescence thermometry can be a solution to this need. We review the various aspects of luminescence thermometry, including different types of luminescence measurements and the numerous materials used as luminescence sensors. We end the article by highlighting other physical quantities that can be measured by luminescence (e.g., pressure, electric field strength, magnetic field strength), and provide a brief overview of applications of luminescence thermometry in biomedicine.

Functional nanomaterials have attracted significant attention in a variety of research fields (in particular, in the healthcare system) because of the easily controllable morphology, their high chemical and environmental stability, biocompatibility, and unique optoelectronic and sensing properties. The sensing properties of nanomaterials can be used to detect biomolecules such as cholesterol. Over the past few decades, remarkable progress has been made in the production of cholesterol biosensors that contain nanomaterials as the key component. In this article, various nanomaterials for the electrochemical sensing of cholesterol were reviewed. Cholesterol biosensors are recognized tools in the clinical diagnosis of cardiovascular diseases (CVDs). The function of nanomaterials in cholesterol biosensors were thoroughly discussed. In this study, different pathways for the sensing of cholesterol with functional nanomaterials were investigated.

Compared with solid scintillators, liquid scintillators have limited capability in dosimetry and radiography due to their relatively low light yields. Here, we report a new generation of highly efficient and low-cost liquid scintillators constructed by surface hybridisation of colloidal metal halide perovskite CsPbA3 (A: Cl, Br, I) nanocrystals (NCs) with organic molecules (2,5-diphenyloxazole). The hybrid liquid scintillators, compared to state-of-the-art CsI and Gd2O2S, demonstrate markedly highly competitive radioluminescence quantum yields under X-ray irradiation typically employed in diagnosis and treatment. Experimental and theoretical analyses suggest that the enhanced quantum yield is associated with X-ray photon-induced charge transfer from the organic molecules to the NCs. High-resolution X-ray imaging is demonstrated using a hybrid CsPbBr3 NC-based liquid scintillator. The novel X-ray scintillation mechanism in our hybrid scintillators could be extended to enhance the quantum yield of various types of scintillators, enabling low-dose radiation detection in various fields, including fundamental science and imaging., Optics: Hybrid liquid scintillator with enhanced light output A hybrid liquid scintillator could be used in low-dose radiation detectors for use in imaging applications and scientific research. Highly sensitive X-ray detection is increasingly being used in industrial and military applications and for fundamental scientific research. Although liquid scintillators are more resilient to damage from exposure to intense radiation than crystalline or plastic scintillators, they have relatively low density and low radioluminescence quantum yields, both of which are critical for achieving high resolution and contrast in X-ray imaging. Now, a team of Korean researchers led by Hyunsik Im from Dongguk University has created a liquid scintillator detector made from colloidal perovskite metal halide nanocrystals and organic molecules with a significantly enhanced quantum yield. The novel device could see use in a wide range of X-ray technologies that require high-performance detectors and imagers.

Random polythiophene polymers are characterized by the arbitrary sequences of monomeric units along polymer backbones. These untailored orientations generally result in the twisting of thiophene rings out of the conjugation planarity in addition to steric repulsions experienced among substituted alkyl chains. These tendencies have limited close polymer packing, which has been detrimental to charge transport in these moieties. To ameliorate charge transport in these classes of polymers, we make use of simple Stille coupling polymerization to synthesize highly random polythiophene polymers. We induced a positive microstructural change between polymer chains by attuning the ratio between alkyl-substituted and nonalkyl-substituted monomer units along the backbones. The optimized random polythiophene was found to have enhanced intermolecular interaction, increased size of crystallites, and stronger tendency to take edge orientation compared with both regiorandom and regioregular poly(3-hexylthiophene) polymers. Incorporation of the optimized random polythiophene as an active material in solid-state electrolyte-gated organic field-effect transistors exhibited better performance than the control device using regioregular poly(3-hexylthiophene), with a high hole mobility up to 4.52 cm

A binder-free process for the electrode preparation for supercapacitor application was suggested by drop casting graphene nanoplatelets on a carbon fiber (GnP@CF) followed by electrodeposition of Ni nanoparticles (NPs). The microstructure of the electrode showed that Ni was homogeneously distributed over the surface of the GnP@CF. XRD analysis confirmed the cubic structure of metallic Ni NPs. The Ni-GnP@CF electrode showed excellent pseudocapacitive behavior in alkaline solution by exhibiting a specific capacitance of 480 F/g at 1.0 A/g, while it was 375 F/g for Ni@CF. The low value of series resistance of Ni-GnP@CF (1 &Omega, ) was attributed to the high capacitance. The enhanced capacitance of the electrode could be correlated to the highly nanoporous structure of the composite material, synergetic effect of the electrical double layer charge-storage properties of graphene, and the pseudocapacitive nature of Ni NPs.

There is an ongoing drive to search for low-temperature processed, stable and efficient electron transport layers (ETLs) for perovskite solar cells (PSCs). Herein, we report, for the first time, the use of a MoS2 thin layer as the ETL for PSCs. MoS2 transparent thin films are directly synthesized on the glass/fluorine doped tin oxide (FTO) substrate by using microwave irradiation. The electrical characteristics of the MoS2 thin film are measured and compared with state-of-the-art efficient electron transporting materials like TiO2 and SnO2. The perovskite solar cells fabricated with the device structure, glass/FTO/MoS2/perovskite/po-spiro-OMeTAD/Au, exhibit a power conversion efficiency (PCE) of 13.1%, which is close to the PCEs obtained from compact TiO2 and SnO2 ETL based PSCs. Good transparency in the visible region (400–900 nm), high electrical conductivity and better charge transfer properties as well as low-temperature synthesis make the MoS2 thin film useful for energy harvesting and other optoelectronic device applications.

Tin based perovskite solar cells (Sn-PSCs) has emerged as a viable solution for the fabrication of low toxic PSCs. However, the rapid crystallization process of tin halide perovskite compounds often result in severe elctronic defects which limits the open circuit voltage (VOC) of the overall PSC. In this work, we report on the successful implementation of a bifunctional compound- Hydroxylamine Hydrochloride (HaHc) with FASnI3 perovksite to reduce the electronic defects. The hydroxyl group in the HaHc formed a hydrogen bond with iodide ion in FASnI3 perovskite system and stabilizes the overall structure, which is evidenced by nuclear magnetic resonance spectroscopy and first-principle calculations. Additionally, the Cl- ion of the HaHc co-ordinates with the under coordinated Sn2+ ions of the FASnI3 perovskite and induces crystal growth along the direction with enhanced crystallinity. Collectively with these dual aspects, the HaHc reduces the electronic defects of the FASnI3 perovskite film. With an optimized concentration of HaHc added with the FASnI3, the corresponding Sn-PSCs showed improved VOC up to 0.676V and power conversion efficiency of 9.18%. Additionaly, the bi-functional HaHc is effective to stabilize the FASnI3 system and exhibited light soaking stablity up to 500 h for the respective Sn-PSCs.

Sn-based perovskite solar cells (PSCs) featuring high performance and long-term stability are very challenging because Sn2+ is relatively prone to oxidation. Here, we have performed coadditive engineering with 5-ammonium valeric acid iodide (5-AVAI) for FASnI3-based perovskite films. From the morphological, structural, and elemental analyses, we observed that 5-AVAI affects the crystal growth of perovskites through its hydrogen bond with I– of the SnI64– octahedral. As a result, pinhole-free homogeneous and stable Sn-based perovskite films form over a large area with lower Sn4+ content. This made us able to enhance the power conversion efficiency (PCE) for Sn-based PSCs up to 7% in a 0.25 cm2 aperture area. Most importantly, the 5-AVAI added PSCs showed a record stability and maintained their initial PCE under 1 sun continuous illumination at maximum power point tracking for 100 h.

Thin film of metallic Cu nanoparticles was synthesized by a one-pot chemical reduction method at ambient temperature. Cu(II) acetate monohydrate and hydrazine monohydrate were used as precursor and reducing agent without additional surfactants to form uniform layer of Cu nanoparticle layer on a glass substrate (Cu/G). The XRD and the effectiveness of the electrocatalytic and catalytic properties of the Cu/G have been applied for an amperometric detection of glucose and for the chemical reduction of 4-nitrophenol. The former exhibited the detection limit as low as 2.47 μM with a linear range of 0.01–0.2 mM, while the latter showed the efficient catalytic activity with a high rate constant of 0.503/min. The current method suggested in this work might be useful for the fabrication of glass-based Cu nanoparticles electrodes for industrial and biomedical applications.

The stability of perovskite solar cells (PSCs) are critically related to the perovskite crystal morphology and film quality, hence controlling the perovskite film formation is one of the key concerns. In this study, we have used four anti-solvents- toluene, chlorobenzene, p-xylene and ether to fabricate high quality CH3NH3PbI3 perovskite films. We investigated the surface morphology, optical and structural properties of the corresponding perovskite films. Consequently, PSCs with variation of these anti-solvents were fabricated and the respective photovoltaic performances over a period of 30 days in dark and under air mass 1.5G sunlight conditions have been observed. Our analyses onto the post fabrication of PSCs highlight that, the perovskite films formed by toluene, chlorobenzene and p-xylene treatment results in high efficient and stable PSCs in dark. Interestingly, the ether treated PSC had no photovoltaic response after 10 days. The toluene and chlorobenzene treated PSCs showed stable device performance and retained 90% of their initial power conversion efficiency even after 30 days light soaking. The p-xylene treated PSCs showed unstable performance during the same light soaking period.

Low temperature processed Perovskite solar cells (PSCs) are popular due to their potential for scalable production. In this work, we report reduced Graphene Oxide (r-GO)/copper (I) thiocyanate (CuSCN) as an efficient bilayer hole transport layer (HTL) for low temperature processed inverted planar PSCs. We have systematically optimized the thickness of CuSCN interlayer at the r-GO/MAPbI3 interface resulting in bilayer HTL structure to enhance the stability and photovoltaic performance of low temperature processed r-GO HTL based PSCs with a standard surface area of 1.02 cm2. With matched valence band energy level, the r-GO/CuSCN bilayer HTL based PSCs showed high power conversion efficiency of 14.28%, thanks to the improved open circuit voltage (VOC) compared to the only r-GO based PSC. Moreover, enhanced stability has been observed for the r-GO/CuSCN based PSCs which retained over 90% of its initial efficiency after 100 h light soaking measured under continuous AM 1.5 sun illumination.

For the fabrication of efficient Sn-based perovskite solar cells (PSCs), deposition of uniform and pinhole-free perovskite films with low Sn4+ content remains a crucial factor. In this work, we present a coadditive engineering process by introduction of hydrazinium chloride (N2H5Cl) in a single precursor solvent system to fabricate FASnI3 perovskite films. The successful integration of N2H5Cl results in reduced concentration of Sn4+ content by 20% in the FASnI3 film leading to suppressed carrier recombination and pinhole-free uniform coverage. These remarkable improvements in the FASnI3 film results in power conversion efficiency (PCE) of Sn-based PSC up to 5.4% due to a significant increase in open-circuit voltage. Moreover, the best PSC without encapsulation showed stable shelf life up to 1000 h while retaining 65% of its initial PCE.

This study demonstrated a single-step potentiostatic method for the electrodeposition of copper (I) sulfide (Cu2S) nanoparticles onto fluorine-doped tin oxide (FTO) electrode from an aqueous solution of CuCl2 and thiourea (TU) to develop counter electrodes (CEs) for quantum-dot sensitized solar cells (QDSSCs). The homogeneously distributed and optimized Cu2S–CE exhibited an improved catalytic activity in the reduction of polysulfide (S2−/Sn2−) electrolyte, which resulted in a power conversion efficiency (PCE) of 4.24% with a short-circuit current density (Jsc), open-circuit voltage (Voc), and fill factor (FF) of 19.60 mA/cm2, 0.445 V, and 48.62%, respectively, for PbS/CdS/ZnS QDs sensitized QDSSCs, while the Pt counterpart exhibited a PCE of 1.17%. The superior photovoltaic performance of this Cu2S–CEs based QDSSC compared to the Pt counterpart is due to its greater electrocatalytic activity and lower charge transfer resistance (RCT) at the Cu2S–CEs/(S2−/Sn2−) interface. This strategy provides an effective, low-cost, and non-Pt electrode for QDSSCs, which is promising for other electrochemical applications.

Nanostructured copper–cobalt based spinel [(Cu0.30Co0.70)Co2O4] was employed as an electrocatalyst in the hydrogen peroxide (H2O2) reduction reaction (HRR). Both nanoparticles and nanoneedles co-existed in the (Cu0.30Co0.70)Co2O4 spinel, which exhibited a high intrinsic electrical conductivity and surface-to-volume ratio, resulting therefore in a large electrochemically active surface area for the HRR. In addition, (Cu0.30Co0.70)Co2O4 showed an onset potential at approximately −0.14 V in the HRR, with a limiting current density of ∼104 mA/cm2 at −0.43 V. The synthesised material followed the direct HRR pathway and exhibited good stability. In addition, the HRR activity of (Cu0.30Co0.70)Co2O4 was comparable to that of commercial Pt/C electrodes. The present results therefore demonstrate the significant potential of (Cu0.30Co0.70)Co2O4 for future applications in fuel cells as a cathode catalyst.

This review summarizes the results of studies on the selective dissolution and extraction of Fe, Cr, Cu, and Zn by ionic liquids, as an alternative to the use of conventional molten salts or pickling agents, for various types of steel. Ionic liquids are classified according to the metals, metal ions, and metal oxides by which they can be extracted or dissolved. The results of the metal extraction efficiency per unit time presented in the literature are summarized in a simple unified graphic format. This provides a comparative understanding of the most efficient ionic liquid for the extraction of specific metals.

Dye-sensitized photovoltaic cells (DSPVs) have great potential in indoor photovoltaic applications for light energy recycling because of their exceptional light-harvesting capability under ambient illumination conditions. The feasibility of DSPVs for use in ambient energy harvesting is verified by their record-high power-conversion efficiency (PCE) of over 30% under indoor illumination conditions, colorful esthetics, cost-effectiveness, stable device performance, and PCE retention of up to 99%. This review provides an insightful overview of the application of DSPVs under the illumination of diffuse and low-intensity light. The key foci of this study are the synergistic impacts of various factors, including the design of dyes, composition of electrolytes, long-term stability, effect of TiO2 mesoporous films, and blocking layers on the indoor performance of DSPVs. Additionally, the review touches upon the commercial aspects of DSPVs that operate under low light intensities, and it provides a critical perspective.

With the emergence of Internet of Things, dye-sensitized photovoltaics (DSPVs) have attracted considerable interest for indoor energy harvesting over the past decade. In this study, a cosensitization approach is applied by mixing ruthenium-based dyes to achieve an increased DSPV performance under low-intensity light conditions. The optimized cosensitized DSPV exhibits an excellent power-conversion efficiency of about 20.7% under a 500-lx light-emitting diode illumination, superior to those of single N719 (16.1%) and N749 (14.8%) under the same illumination conditions. The improved performance of the cosensitized device can be attributed to the panchromatic absorption of the mixed dyes. In addition, an electrochemical impedance analysis is performed to analyze the charge transfer kinetics of the single and cosensitized devices at the TiO2/dye/electrolyte interface. The exceptional indoor performance of the cosensitized DSPV can be attributed to the increased external quantum efficiency, sharp increase in the current density with an increased broadening of the absorption window, and balanced charge transport characteristics. The findings of this study suggest that cosensitization is a useful technique for the realization of high indoor performances of DSPVs.

Organosulfonium cations have attracted growing attention over conventional organoammonium cations for the development of moisture-stable hybrid organic–inorganic metal halide perovskite solar cells (PSCs). Herein, the synthesis of a moisture-stable trimethylsulfoxonium lead triiodide ((CH3)3SOPbI3 or TMSOPbI3) perovskite is described via a two-step solution process in an aqueous medium. The synthesized TMSOPbI3 exhibits a one-dimensional nanorod array with an optical bandgap of 2.30 eV and a hexagonal crystal structure. In addition, the fabricated fluorine-doped tin oxide/compact-TiO2/mesoporous-TiO2/TMSOPbI3/CuSCN/Au PSC device generates a maximum power conversion efficiency (PCE) of 2.23% with a good moisture stability at ambient temperature and relative humidity (50%) with no PCE loss during 336 h and no change in the crystal structure during 50 days. The high moisture stability of the device is attributed to the absence of hydrogen bonding between the trimethylsulfoxonium (TMSO+) cation and the H2O molecules along with strong electrostatic interactions between the TMSO+ and [PbI6]4- polyhedra in the TMSOPbI3. This research has demonstrated that TMSO+ is suitable for fabricating a stable perovskite-like material with good optoelectronic properties and is a promising material for practical applications.