Electron Transfer Layer Research Articles

Two-dimensional nickel nanosheets coupled with Zn0.5Cd0.5S nanocrystals for highly improved visible-light photocatalytic H2 production

Ni-based precious-metal-free cocatalysts have attracted copious attention due to their nature-friendly and cost-effectiveness compared with platinum (Pt) during photocatalytic H2 evolution. However, the typical morphologies and structures of Ni-based cocatalysts (e.g., Ni) focus on the zero-dimensional (0D) nanoparticles. Herein, we demonstrate a two-dimensional (2D) nickel nanosheets cocatalyst decorated Zn0.5Cd0.5S nanocrystals that pays attention to visible-light-motivated photocatalytic H2 generation. By rationally introducing Ni nanosheets to modify Zn0.5Cd0.5S nanoparticles, a series of unique 2D/0D Ni/Zn0.5Cd0.5S nanohybrids with different Ni contents were synthesized. The optimized Ni-5%/Zn0.5Cd0.5S composite possesses a high H2 production rate of 5930μmolh−1g−1 upon visible-light (λ > 420 nm) illumination, which was about 33.7 and 15.4-fold more elevated than those of Zn0.5Cd0.5S nanocrystals, and Pt/Zn0.5Cd0.5S, respectively. Combining photoelectrochemical (PEC) and photoluminescence (PL) studies, the conspicuous enhancement in photocatalytic H2 generation was stemmed from the Ni nanosheets cocatalyst act as an electron-transfer layer to extract photoexcited electrons from Zn0.5Cd0.5S and offer enormous reaction sites for H2 production. This work verifies Ni nanosheets' capability for photocatalytic water splitting. The Ni/Zn0.5Cd0.5S composed of magnetic metal and ternary metal sulfide can be extended to other photocatalytic applications, such as dyes degradation and CO2 reduction.

Enhanced electrical properties of Li-salts doped mesoporous TiO2 in perovskite solar cells

<h2>Summary</h2> The charge transferability of the electron transfer layers (ETLs) is important for achieving high performance in mesoscopic (mp) perovskite solar cells (PSCs). However, because of the low electron extraction efficiency of TiO₂, lithium doping is essentially required. In this work, we compared the electrical properties of mp-TiO₂ doped with Li-salts with different anions—LiTFSI, Li₂CO₃, LiCl, and LiF. Interestingly, we found that the anions of the Li-salt dopants affect the electrical properties of the ETLs and the solar cell performance. The Li₂CO₃ doping of mp-TiO₂ led to conduction bands deeper than those of pristine mp-TiO₂ or other doped mp-TiO₂. The maximum efficiency of 25.28% and certified efficiency of 24.68% (Newport) was obtained by using Li₂CO₃ dopant. This optimization of the ETLs properties is expected to greatly contribute to the progress of PSCs by leading to further increases in their efficiency.

KNbO3]1-x[BaCo1/2Nb1/2O3-δ]x inorganic perovskite oxide coupled with TiO2 nanorods photoelectrode: Toward efficient enhancement of photoelectrochemical properties

Inorganic perovskite oxide photosensitizer have shown versatile practical applications, owing to fruitful chemistries of photoelectric materials. This work reports a straightforward and general protocol via the use of Co/Ba co-doped KNbO3 (KBCNO) photosensitizer coupled with TiO2 nanorods to boost photoelectricity property. In the representative system, KBCNO with different doping concentrations and TiO2 nanorods were used as photosensitizer and electron transfer layer, respectively. The synthetic process implicated that KBCNO with various concentration prepared by pulsed laser deposition technique and TiO2 nanorods were used as an active optical absorption layer and electrode, and the specific physicochemical, optical characterization and photoelectrochemical (PEC) performance were all discussed in detail in the detection of the obtained photoelectrodes. This work is also an effective extension of previous studies on the category of inorganic perovskite oxide photosensitizers, which has not been reported by other research group. Given that KNbO3-based compounds can be easily obtained in abundance and variety, this work enjoys great advantages in PEC performance of numerous other inorganic perovskite oxide photosensitizer.

Thiazole‐Modified C3N4 Interfacial Layer for Defect Passivation and Charge Transport Promotion in Perovskite Solar Cells

Despite the conspicuous achievements in perovskite solar cells (PSCs), further improvement of the power conversion efficiency (PCE) is hindered by substantially detrimental carrier recombination resulting from the high interfacial charge defect density and inferior charge transport kinetics. Herein, an interface engineering strategy is developed to introduce a Lewis base thiophene or thiazole–modified C3N4 layer at the electron transfer layer (ETL)/perovskite interface to constitute a stepwise energy band alignment and passivate defects at interfaces of the perovskite film. Attributed to its well‐matched energy level with TiO2 and perovskite, the charge extraction efficiency and charge transfer dynamics can be promoted remarkably, greatly inhibiting charge recombination at the interface. Furthermore, thiophene and thiazole can donate the lone pair electrons in S or N atoms to undercoordinated Pb2+, which effectively passivates the electronic trap states caused by halogen vacancies, thereby greatly minimizing trap‐assisted nonradiative recombination in the PSCs. Eventually, the thiazole–C3N4/perovskite‐based devices acquire an outstanding efficiency of 19.23%, supported by an enhanced open‐circuit voltage (VOC) of 1.11 V with improved moisture stability. This work provides an avenue for interfacial energy level modulation and defect passivation strategies for a rational interface microstructure design for meliorating the performance of PSCs.

Morphological improvement of CH3NH3PbI3 films using blended solvents for perovskite solar cells

Perovskite solar cells with the structure of glass/florine-doped tin oxide (FTO)/electron transfer layer (ETL)/perovskite/hole transfer layer (HTL)/Ag were fabricated. The effects of blending solvents and thermal annealing on the surface morphology, structural, and optical properties of perovskite (CH3NH3PbI3) active layer were investigated. The active layer was optimized by adding 2-butanol (2-BTA) as an eco-friendly solvent into methyl ammonium iodide (MAI) solution used for spin coating on PbI2/(dimethylformamide (DMF)+dimethyl sulfoxide (DMSO)) film in the second step. The resulting morphology of CH3NH3PbI3 films was smooth and pinholes in the films were also reduced without change in the structure. The effects of thermal annealing on the surface morphology and structural properties of active layer were also studied. The fabricated device for the optimized condition showed the maximum power conversion efficiency (PCE) of ~8.6%.

Graphene assisted crystallization and charge extraction for efficient and stable perovskite solar cells free of a hole-transport layer.

In recent times, perovskite solar cells (PSCs) have been of wide interest in solar energy research, which has ushered in a new era for photovoltaic power sources through the incredible enhancement in their power conversion efficiency (PCE). However, several serious challenges still face their high efficiency: upscaling and commercialization of the fabricated devices, including long-term stability as well as the humid environment conditions of the functional cells. To overcome these obstacles, stable graphene (G) materials with tunable electronic features have been used to assist the crystallization as well as the charge extraction inside the device configuration. Nonetheless, the hole transport layer (HTL)-free PSCs based on graphene materials exhibit unpredictable results, including a high efficiency and long-term stability even in the conditions of an ambient air atmosphere. Herein, we combine graphene materials into a mesoporous TiO2 electron transfer layer (ETL) to improve the coverage and crystallinity of the perovskite material and minimize charge recombination to augment both the stability and efficiency of the fabricated mixed cation PSCs in ambient air, even in the absence of a HTL. Our results demonstrate that an optimized PSC in the presence of different percentages of graphene materials displays a PCE of up to 17% in the case of a G:TiO2 ETL doped with 1.5% graphene. With this coverage and crystallinity amendment approach, we show hysteresis-free and stable PSCs, with less decomposition after ∼3000 h of storage under a moist ambient atmosphere. This work focuses on the originalities of the materials, expenses, and the assembling of stable and effective perovskite solar cells.

Graphdiyne oxide doped SnO2electron transport layer for high performance perovskite solar cells

Graphdiyne oxide-doped SnO2is applied as a novel electron transfer layer for the preparation of high-performance perovskite devices.

3D Device Simulation and First Demonstration of BaSi2 Thin Film Solar Cells

Barium disilicide (BaSi2) shows great promise as a new material for thin film solar cells (Fig. 1) [1]. It has a suitable bandgap of 1.3 eV, a large optical absorption coefficient of 3×104 cm−1 for a photon energy of 1.5 eV, and a large minority-carrier diffusion length of about 10 μm. Furthermore, it is composed of only earth abundant elements and highly stable. Therefore, BaSi2 can be used for future terawatt-class power generation. We have achieved the operation of BaSi2 homojunction solar cells (Fig. 2) [2]. In this structure, an open-circuit voltage V OC beyond 0.8 V and a conversion efficiency (η) beyond 25% are expected [3]. However, the achieved η was very small. In this study, three-dimensional (3D) optical simulation using a 3D pyramid texture that is effective in preventing reflection was performed on a BaSi2 solar cells in order to increase the photocurrent. Futhermore, we suggested a new device structure using Al-doped ZnO (AZO) electron transfer layer (ETL).In this study, we performed a 3D optical simulation using the GenPro4 model developed at TU Delft [4]. In this simulation, the absorptance of each layer is calculated as a function of wavelength λ. We introduced the 3D-texture structure on the front and back surfaces of the Si substrate to investigate the anti-reflection and light trapping effects (Fig. 3(a)). The thickness and complex refractive index n + ik of every layer are given as input (Fig. 3 (b,c)). In addition, to increase light absorption in BaSi2 light absorber layers, we investigated n+-AZO/p-BaSi2 heterojunction solar cells in which the ETL was changed from n+-BaSi2 to n+-AZO.The absorption spectra of the BaSi2 homojunction solar cells are shown Fig. 5. By changing the front surface structure from flat to texture, the reflectance in the λ range 700 – 1200 nm reduced and the J ph in p-BaSi2 increased by 1.2 mA/cm2. On the other hand, the light trapping effect by the texture structure on the back surface could not be observed well. This is probably because almost all the transmitted light was absorbed by the Si substrate before reaching the back surface. Photons with λ between 800 and 1200 nm are absorbed in the Si substrate. In addition, it was found that the largest factor inhibiting light absorption in the p-BaSi2 layer was parasitic absorption in the ETL n+-BaSi2. This parasitic absorption is unavoidable when BaSi2 is used for ETL, because BaSi2 has a very large light absorption coefficient.Other thin film solar cells, e.g. CIGS, Perovskite, are a kind of heterojunction solar cells which consist of p-type absorbers and n-type window layers. The wide bandgap of the window layer allows more photons to reach the absorber layer. Another advantage of a heterojunction is that the recombination in the wide bandgap window layer is quite low in comparison to that in homojunctions. Now based on these basics, we proposed n+-AZO/p-BaSi2 heterojunction solar cell in which the ETL was changed from n+-BaSi2 to n+-AZO (Fig. 6). Because the E g of AZO is very large (~3.3 eV), much light can be transfer to BaSi2 light absorber layer. The absorption spectra of the n+-AZO/p-BaSi2 heterojunction solar cells were shown in Fig. 7. The parasitic absorption in the ETL was significantly reduced. The J ph in the p-BaSi2 layer increased by more than 10 mA/cm2 compared with that of the homojunction solar cells and reached a maximum of 30.23 mA/cm2 using the front textured surface.Based on these simulated results, we tried to form n+-AZO/p-BaSi2 heterojunction solar cells experimentally. p-BaSi2 and p+-BaSi2 films were grown epitaxially on a Cz-p+-Si(111) substrate by molecular beam epitaxy, and ZnO and AZO were deposited by sputtering. The J-V characteristics under AM1.5 illumination and the internal quantum efficiency (IQE) spectrum for an n+-AZO/p-BaSi2 heterojunction solar cell are shown in Fig. 8. It shows η = 0.04%, a short-circuit current density J SC of 3.7 mA/cm2, and an V OC of 50 mV. IQE exceeded 30% at λ = 600 nm. This efficiency is almost the same value as that obtained for BaSi2-pn homojunction solar cells. Therefore, we can state that we succeeded the demonstration of n+-AZO/p-BaSi2 heterojunction solar cells for the first time.[1] T. Suemasu and N. Usami, J. Phys. D: Appl. Phys. 50, 023001 (2017).[2] K. Kodama et al., Appl. Phys. Express 12, 041005 (2019).[3] T. Suemasu, Jpn. J. Appl. Phys. 54, 07JA01 (2015).[4] R. Santbergen et al., IEEE J. Photovoltaics, 7, no. 3, 919–926 (2017). Figure 1

Vacuum Dual-Source Thermal-Deposited Lead-Free Cs3Cu2I5 Films with High Photoluminescence Quantum Yield for Deep-Blue Light-Emitting Diodes.

Deep-blue emitters are greatly desirable for preparing white light-emitting diodes and enhancing the color gamut of full-color display. The deep-blue lead halide perovskite light-emitting diodes (PeLEDs) exhibit far inferior performance compared to green and red counterparts and suffer from lead toxicity, hampering their applications. Nontoxic, stable, and wide band gap zero-dimensional (0D) Cs3Cu2I5 with relatively high exciton binding energy has great potential as deep-blue emitters. However, the development of PeLEDs remains a huge challenge due to the difficulties in preparing a high-quality Cs3Cu2I5 film and device design, arising from an inherent wide band gap together with deep ionization potential. Here, a continuous and pin-hole-free Cs3Cu2I5 thin film with deep-blue emission centered at 440 nm was prepared by the dual-source thermal evaporation approach, and a high photoluminescence quantum yield of 58% was achieved, corresponding to significant enhancement of 61% compared with that of the Cs3Cu2I5 thin film synthesized by solution processes. Furthermore, saturated deep-blue PeLEDs at the Commission Internationale de L'Eclairage (CIE) coordinates (0.15, 0.08) were obtained by employing an electron-transfer layer composed of a 1,4,5,8,9,11-hexa-azatriphenylene hexacarboni-trile (HAT-CN) and N,N'-bis(naphthalen-1-yl)-N,N'-bis(phenyl)benzidine (NPB) organic heterojunction to realize the effective hole blocking, rendering an external quantum efficiency of approximately 0.1%. These results will be extensively beneficial to wide band gap material and device preparation.

Highly stable perovskite solar cells based on perovskite/NiO-graphene composites and NiO interface with 25.9 mA/cm2 photocurrent density and 20.8% efficiency

Perovskite solar cells (PSCs) demonstrated a record-high power conversion efficiency, but they have instability issues attributed to the degradation of materials and device performance. To overcome the instability problem and performance degradation, various methods have been proposed, but still need a comprehensive solution. Here, we propose an innovative way of insuring device performance and long-term stability by utilizing functional composites of perovskite, nickle oxide and graphene into device structures. We fabricated the PSCs based on MAPbI 3−x Cl x /NiO-graphene photoactive composite and NiO interface layer. Compared to the pristine perovskite cells, the champion device based on the photoactive composites with NiO interface showed remarkably high photocurrent density of 25.9 mA/cm 2 (i.e., 95.2% of theoretical maximum) and power conversion efficiency of 20.8% without J-V hysteresis. More impressively, unencapsulated cells showed significant improvement of thermal- and photo- and long-term air-stability with retaining 97–100% of the initial values of performance parameters over 310 days under ambient conditions. Schematic illustration of a perovskite solar cell structure based on MAPbI 3−x Cl x /NiO-rGO composite photoactive layer and NiO interface formed on the SrTiO 3 /Al 2 O 3 -graphene electron transfer layer, exhibiting the mechanism of charge carrier separation and conduction through graphene and connected NiO nanoparticles and blocking moisture and oxygen infiltration. • Highly stable and efficient composites-based perovskite solar cells. • Perovskite/NiO-graphene photoactive composite and NiO interface layer. • Remarkably high photocurrent density and power conversion efficiency without J-V hysteresis. • Significant improvement of thermal- and photo- and air-stability with retaining 97–100% of device performance over 310 days.

Primary color generation from white organic light-emitting diodes using a cavity control layer for AR/VR applications

Abstract In this paper, we report primary color generation method from white top-emission organic light emitting diodes (WTEOLEDs) by applying cavity control layer (CCL) for achieving high resolution display. In order to realize primary colors, we applied high efficiency two-stack WTEOLED structure with solution processed indium zinc oxide CCL. Using optically designed two-stack WTEOLED with CCL, we fabricated red, green, and blue TEOLEDs with current efficiency of 34.9, 79.5, and 3.4 cd/A, respectively. However, there is an issue of intense blue emission in the red color device due to its cavity condition. To suppress this blue emission, silver nanoparticles doped electron transfer layer and rubrene doped hole transport layer methods were successively used due to their high absorption in the blue region. By applying these two methods together, top-emission red device showed 80% reduction in blue color intensity.

Low-Temperature Thermally Evaporated SnO₂ Based Electron Transporting Layer for Perovskite Solar Cells with Annealing Process.

Perovskite solar cells (PSCs) represent the third generation of solar cells that comprise a semiconductor electrode, a counter electrode, and an electrolyte. Perovskite solar cells (PSCs) have been comprehensively researched and led to an impressive improvement in a short period of time as cheaper alternatives to silicon solar cells due to their high energy-conversion efficiency and low production cost. Tin oxide (SnO₂) has attracted attention as a promising candidate for electron transport material of perovskite solar cells, because it can be easily processed by low annealing temperature and solution processing method. However, in the fabrication of SnO₂ electron transfer layer (ETL) via the conventional solution method, it is greatly difficult to increase the size of the substrate by the solution treatment method or to commercialize it. In this work, we report the photovoltaic characteristics of SnO₂ based electron transport layer for perovskite solar cells (PSCs) fabricated by the thermal-evaporation processing method. The deposited SnO₂ layer with the thermal evaporator is known to be not crystallographically stable. To solve this problem, we performed the annealing process at relatively low temperature (below 200 °C). As a result, we could confirm the optimum annealing temperature and we could demonstrate PSCs with thermally deposited SnO₂ as the compact electron transport layer through a low-temperature annealing process. It would contribute to new opportunities in commercialization and development of perovskite solar cells.

Design of Ag/g-C3N4 on TiO2 nanotree arrays via ultrasonic-assisted spin coating as an efficient photoanode for solar water oxidation: Morphology modification and junction improvement

Graphitic carbon nitride (g-C3N4) has been extensively studied as a model of polymeric semiconductor material in photoelectrochemical (PEC) water oxidation reaction; however, its low PEC performance is still a concern of significant importance among researchers. Herein, we did a novel host-guest design of a photoanode device comprising three dimensional (3D) TiO2 nanotree (NT) arrays as an electron transfer layer (ESL) and Ag/g-C3N4 heterojunction as a photo absorber layer. In this design, 3D TiO2 NT arrays synthesized via a hydrothermal growth treatment were deposited with an alcoholic suspension of Ag/g-C3N4 using different coating methods such as drop casting, spin coating, and ultrasonic assisted-spin (U-spin) coating methods. The optimized photoanode prepared via U-spin coating exhibited a remarkable photocurrent density of 1.4 mA cm−2 at 1.23 V vs. RHE and a negatively shifted onset potential of 0.2 V in 1.0 M KOH when it was illuminated from the backside using a Xenon lamp (150 W) equipped with a 400 nm cut off filter. This hierarchical 3D design photoanode demonstrated constant stability during the water oxidation reaction for at least 8 h.

A novel leaves and needles like TiO2 (LNT) electron transfer layer (ETL) as an alternative to meso-porous TiO2 electron transfer layer (ETL) in perovskite solar cell

Abstract Two perovskite solar cells one with leaves and needles like TiO2 (LNT) and other with meso-porous TiO2 as electron transfer layer (ETL) were fabricated. The perovskite solar cell structure FTO/Compact-TiO2/LNT/CH3NH3PbBr3/Spiro-OMeTAD/Ag with leaves and needles like TiO2 electron collector, exhibit high efficiency up to 9% being supported by high open-circuit voltage and fill factor up to 0.8 V and 0.89, respectively. The second perovskite solar cell structure FTO/Compact-TiO2/Meso-porous TiO2/CH3NH3PbBr3/Spiro-OMeTAD/Ag with meso-porous TiO2 electron collector, efficiency is 6.2% with open-circuit voltage and fill factor up to 0.77 V and 0.71 respectively. As compared to meso-porous TiO2 electron collector layer, leaves and needles like TiO2 has better electron band alignment with compact TiO2 as hole blocking layer and hence, results in higher efficiency.

Contrasting Electron and Hole Transfer Dynamics from CH(NH2)2PbI3 Perovskite Quantum Dots to Charge Transport Layers

In this work, the ultrafast transient absorption spectroscopy (TAs) was utilized to first investigate the charge transfer from the emerging FAPbI3 (FA = CH(NH2)2) perovskite quantum dots (PQDs) to charge transport layers. Specifically, we compared the TAs in pure FAPbI3 PQDs, PQDs grown with both electron and hole transfer layers (ETL and HTL), and PQDs with only ETL or HTL. The TA signals induced by photoexcited electrons decay much faster in PQDs samples with the ETL (~20 ps) compared to the pure FAPbI3 PQDs (&gt;1 ns). These results reveal that electrons can effectively transport between coupled PQDs and transfer to the ETL (TiO2) at a time scale of 20 ps, much faster than the bimolecular charge recombination inside the PQDs (&gt;1 ns), and the electron transfer efficiency is estimated to be close to 100%. In contrast, the temporal evolution of the TA signals in the PQDs with and without HTL exhibit negligible change, and no substantive hole transfer to the HTL (poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], PTAA) occurs within 1 ns. The much slower hole transfer implies the further potential of increasing the overall photo-carrier conversion efficiency through enhancing the hole diffusion length and fine-tuning the coupling between the HTL and PQDs.

21.4% efficiency of perovskite solar cells using BMImI additive in the lead iodide precursor based on carbon nanotubes/TiO2 electron transfer layer

Carbon nanotubes (CNT) are unique one-dimensional structures that have been widely used for enhancing optoelectronic devices because of their fascinating properties. In this work, the impact of multi-walled CNT (MWCNT) on photovoltaic (PV) performance of mesoporous-titanium dioxide (m-TiO2) based perovskite solar cells (PSCs) is investigated. First, the incorporation of 1-Butyl-3-methylimidazolium iodide (BMImI) within the lead iodide (PbI2) precursor caused suppressing PbI2 residue from perovskite (PVK) film as proved via X-ray diffractometer (XRD). The loading of MWCNT in the m-TiO2 electron transfer layer (ETL) led to the formation of PVK with bigger grains and higher crystallinity with improved light absorbance. The power-conversion efficiency (PCE) of the PSC was remarkably boosted to 21.4% for the device containing 0.2% MWCNT versus 12.5% for the control device without any additives. MWCNT loaded in TiO2 provides a fast charge transfer within the ETL, resulting in an improving in the short circuit current (Jsc) value. This can be assigned to an enhanced band level alignment of the m-TiO2 after the incorporation of MWCNT. Moreover, it is found that the loading of MWCNT into m-TiO2 ETL decreases the hysteresis phenomenon and enhances the heat and humidity stability of the PSCs.

Novel core-modulated naphthalenediimides with CN-TFPA as electron transport layer for inverted perovskite solar cells

Herein we report the design and synthesis of two new naphthalenediimide (NDI) chromophores; (2Z,2′Z)-3,3′-(5,5′-(2,7-dioctyl-1,3,6,8-tetraoxo-1,2,3,6,7,8-hexahydrobenzo [lmn][3,8]phenanthroline-4,9-diyl)bis (thiophene-5,2-diyl))bis(2-(4-(trifluoromethyl)phenyl) acrylonitrile) (F1) and (2Z,2′Z)-3,3′-(5,5′-(2,7-dioctyl-1,3,6,8-tetraoxo-1,2,3,6,7,8-hexahydrobenzo[lmn][3,8] phenanthroline-4,9-diyl)bis(thiophene-5,2-diyl))bis(2-(3,5-bis(trifluoroomethyl)phenyl) acrylonitrile) (F2). Both compounds are thermally stable as confirmed by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), and are employed in perovskite solar cells (PSCs), making F1 and F2 promising candidates as electron transfer layers (ETL). Further, F1 and F2 were utilized as electron transport layers (ETLs) in inverted PSC assemblies. The overall power conversion efficiency (PCE) of inverted PSC devices constructed using F1 layer was 10.2 %, with circuit current density (Jsc) of 24.17 mAcm−2 and open circuit voltage (Voc) of 0.81 V, and fill factor (FF) of 52 %, while PSCs constructed using F2 had 9.1 % PCE, Jsc of 24.35 mAcm−2, Voc of 0.83 V, and FF of 45.4 %. The performance of PSCs are mainly attributed to the presence of -CF3 functional groups in F1 and F2.

BiOCl0.875Br0.125/polydopamine functionalized PVDF membrane for highly efficient visible-light-driven photocatalytic degradation of roxarsone and simultaneous arsenic immobilization

A bifunctional membrane modified by BiOCl0.875Br0.125 and polydopamine (PDA) was developed in the current study and employed for the photocatalytic degradation of roxarsone (ROX) under visible-light and simultaneous immobilization of the released inorganic arsenic by sorption. Characterization techniques, such as FESEM, XRD, FTIR-ATR, DRS and XPS were used to characterize as-prepared membranes so as to analyze their structural and functional attributes. Dynamic cyclic experiments indicated that a satisfactory degradation efficiency of ROX (∼100%) could be achieved by the photocatalytic process within 5 h. Simultaneously, the released inorganic arsenic could be completely converted to As(V) and eventually immobilized onto the surface of membrane. The critical reactive oxidation species (ROS) including O2−, h+ and OH contributed to the photodegradation of ROX, and the PDA coating played multiple roles as an adhesive interface, an electron transfer layer, and an active adsorptive layer. Additionally, based on the HPLC-AFS and GC–MS analysis, the major degradation products were detected and the mechanism of ROX degradation and simultaneous arsenic immobilization by BiOCl0.875Br0.125/PDA functionalized PVDF membranes (BPMs) was given, and the reaction pathway of ROX during the photocatalytic/filtration process was also taken into consideration. Combined with the exceptional photocatalytic property and high adsorption capacity of arsenic, the fabricated BPMs may open new opportunities for the control of ROX in water treatment.

Ag nanoparticle-based efficiency enhancement in an inverted organic solar cell

Herein, we demonstrate the improvement in performance of inverted organic solar cells fabricated with an Ag-nanoparticle (Np) modified ZnO-electron transport layer. Ag NP incorporation into the ZnO layer increases light harvesting efficiency of the solar device which untimely improves Jsc of the device. As a result, power conversion efficiency (PCE) of ZnO + Ag Np buffer layer based (ITO/ZnO:Ag NP/P3HT: PCBM/MoO3/Ag) device reaches 3.02% which is 27% higher than ITO/ZnO/P3HT: PCBM/MoO3/Ag device and 55.6% higher than the electron transfer layer(ETL) free (ITO/P3HT: PCBM/MoO3/Ag) control device.

HI-assisted fabrication of Sn-doping TiO2 electron transfer layer for air-processed perovskite solar cells with high efficiency and stability

Effective electron transport layers (ETLs) provide enhanced charge separation and transport, therefore as a vital part in improving the efficiency of planar perovskite solar cells (PSCs). Herein, we report a new synergistic strategy using HI to passivate TiO2 film and surface while incorporating tin element into TiO2 ETL. HI is first used to control the hydrolysis of TiO2 precursors and eliminate oxygen vacancies related trap states. Then, tin element is incorporated into HI-passivated TiO2 precursor solution to construct composite TiO2/SnO2 film, affording increased electron mobility and suitable energy level. Moreover, the entire preparation process is performed under uncontrolled environmental conditions at 150 °C temperatures. Benefiting from the improved quality of the ETLs, the unencapsulated PSCs achieve optimized power conversion efficiency (PCE) of 17.77% with greatly improved stability. After storage in ambient for 1450 h, the device still maintains 92% of its initial efficiency, while hold 79% PCE after 7 h of 1 sun exposure and 86% PCE after heating at 100 °C for 21 h.