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For the first time, [Cu]-catalyzed annulation and direct C–H/C–I couplings were used as key transformations to access new DTT-based hole-transporting materials (HTMs), CHC05–07. Perovskite solar cells with CHC07 display PCEs of up to 14.7%.

Three cyclopenta[2,1-b;3,4-b′]dithiophene (CPDT)-based organic semiconductors LYC-1-LYC-3 consisting of a central dithiolane ring with triarylamine-based side groups were prepared and utilized as h...

Photocatalysis has been regarded as a promising process for pollution removal and green energy. TiO2 nanofibers synthesized by the hydrothermal method presents high crystalline and performs excellently due to the efficient charge transport. For practical use, we designed an autoclave with a 1,000 cm3 of Teflon-liner inside and stainless steel outside for the hydrothermal synthesis of Ag/TiO2 NFs. Various parameters of the process, including reaction temperature, doping concentration, and calcination temperature, were investigated to provide a reliable and optimal process. Through the hydrothermal reaction, TiO2 particles transformed into sodium titanate nanorods, and further refilled the hollow channel. With the proton exchange using diluted hydrochloric acid, the precipitated Ag nanoparticles were leached but appeared again on the surface of Ag/TiO2 nanofibers after the calcination. Silver incorporation enhanced the absorption in the visible region and precipitated onto the TiO2 NFs surface after the optimal calcination, constructing the heterostructure. It dominated the photocatalytic performance of pollutant degradation and water splitting. The unveiling of silver surface precipitation gives a clear illustration in the scaled-up hydrothermal method of Ag/TiO2, providing an efficient way for nanomaterial fabrication.

A new cyclopentadithiophene (CPDT)-based organic small molecule serves as an efficient dopant-free hole transport material (HTM) for perovskite solar cells (PSCs). Upon incorporation of two carbazole groups, the resulting CPDT-based HTM (C-CPDT) shows an impressive power conversion efficiency (PCE) of 19.68% with better stability compared with those of spiro-OMeTAD.

In most research papers, synthesis of organic hole-transporting materials relies on a key-reaction: Stille cross-couplings. This requires tedious prefunctionalizations including the preparation and treatment of unstable organolithium and toxicity-concern organotin reagents. In contrast to traditional multistep synthesis, this work describes that a series of star-shaped small molecules with a carbazole or phenothiazine core can be efficiently synthesized through a shortcut using optimized direct C–H/C–Br cross-couplings as the key step, thus avoiding dealing with the highly reactive organolithium or the toxic organotin species. Device fabrication of perovskite solar cells employing these molecules (6–13) as hole-transporting layers exhibit promising power conversion efficiencies of up to 17.57%.

Two polycyclic heteroarene derivatives, namely, V-1 and V-2, with a diphenanthro[9,10-b:9',10'-d]thiophene (DPT) core tethered with two diphenylaminophenyl or diphenylamino groups were first synthesized and used as hole-transporting materials (HTMs) in perovskite solar cell (PSC) fabrication. The novel HTMs exhibit appropriate energy-level alignment with the perovskite so as to ensure efficient hole transfer from the perovskite to HTMs. V-2 with the diphenylamino substituent on DPT exhibited impressive photovoltaic performance with a power conversion efficiency of 19.32%, which was higher than that of V-1 (18.60%) and the benchmark 2,2',7,7'-tetrakis-(N,N-di-p-methoxyphenyl-amine)-9,9'-spirobifluorene (spiro-OMeTAD) (17.99%), presumably because of a better hole extraction, higher hole mobility, and excellent film-forming ability, which were supported by steady-state photoluminescence (PL), time-resolved PL, the hole mobility experiment, scanning electron microscopy, and atomic force microscopy measurements. Meanwhile, V-2-based PSCs exhibited better long-term durability than that with V-1 and the state-of-the-art spiro-OMeTAD, which is ascribable to the excellent surface morphology and hydrophobicity of the film. This systematic study suggests that DPT-based molecules are good potential candidates as HTMs for achieving high-performance PSCs.

Atmospheric thermal assisted blade coating (TABC) method, which is quick film crystallization and easier fabrication than the commonly used spin-coating process, to prepare a high quality CH3NH3PbI3 perovskite film is investigated in this work. Selection of the perovskite precursor solvents and controlling the ratio of the mixed solvent as well as substrate temperature for perovskite film formation are important factors in this TABC process. Based on the results obtained in this work, substrate temperature is the key factor for managing the perovskite film phase transition which influences the film roughness and crystallinity. Furthermore, the high-quality perovskite films are prepared by perovskite precursors with mixture of solvents containing GBL/DMSO at the ratio from 1/9 to 5/5. By using the optimum substrate temperature of 130 °C and the GBL/DMSO solvent ratio of 1/9 (G01D09) for the preparation of small area n-i-p and p-i-n PSCs as well as the p-i-n type perovskite sub-module, the power conversion efficiencies of 17.55%, 16.90% and 13.03%, respectively, are acquired under the illumination of 100 mW/cm2 (AM 1.5G).

Perovskite solar cells (PSCs) have earned considerable attention and are candidates against the inevitable energy crisis. Even though various successful PSCs have emerged, increasing the PCE by reinforcing charge collection is still a critical issue. The manipulation of carriers between the perovskite active layer and the electron extraction layer (EEL) is essential. Here, we prepared a tin-doped TiO2 (Sn/TiO2) EEL that presented two main polymorphs, anatase and rutile, and successfully fabricated a high-performance planar PSCs. Besides, the band alignment between EEL and perovskite active layer could be optimized by tuning the Sn doping concentration and the ratio of anatase and rutile phases. The intrinsic conductivity, interface morphology, band alignment, and charge carrier dynamic were characterized and the relationship to the photovoltaic performance was clarified. As the Sn ions being doped into TiO2 structure, EEL presented the mixed TiO2 rutile/anatase phase, directly narrowing the bandgap and promoting mobility. Furthermore, the adjustment of the band structure can facilitate electronic transitions. Finally, a promising planar PSC with Sn/TiO2 phase junction EEL achieved a champion PCE of 15.4%.

In this work, two novel tetra-substituted X-shaped molecules X1 and X2 that were constructed with anthracene as the central core and arylamine as the donor groups have been synthesized. The HTMs X1 and X2 were synthesized in two steps from industrially accessible and moderately reasonable beginning reagents. These new HTMs are described in terms of utilization of light absorption, energy level, thermal properties, hole mobility (µh), and film-forming property. The photovoltaic performances of these HTMs were effectively assessed in perovskite solar cells (PSCs). The devices based on these HTMs accomplished an overall efficiency of 16.10% for X1 and 10.25% for X2 under standard conditions (AM 1.5 G and 100 mW cm−2). This precise investigation provides another perspective on the use of HTMs in PSCs with various device configurations.

In this study, polycaprolactone (PCL)- and poly(acrylic acid) (PAA)-based electrospun nanofibers were prepared for the carriers of antimicrobials and designed composite nanofiber mats for chronic wound care. The PCL- and PAA-based electrospun nanofibers were prepared through in situ polymerization starting from PCL and acrylic acid (AA). Different amounts of AA were introduced to improve the hydrophilicity of the PCL electrospun nanofibers. A compatibilizer and a photoinitiator were then added to the electrospinning solution to form a grafted structure composed of PCL and PAA (PCL-g-PAA). The grafted PAA was mainly located on the surface of a PCL nanofiber. The optimization of the composition of PCL, AA, compatibilizer, and photoinitiator was studied, and the PCL-g-PAA electrospun nanofibers were characterized through scanning electron microscopy and 1H-NMR spectroscopy. Results showed that the addition of AA to PCL improved the hydrophilicity of the electrospun PCL nanofibers, and a PCL/AA ratio of 80/20 presented the best composition and had smooth nanofiber morphology. Moreover, poly[2 -(tert-butylaminoethyl) methacrylate]-grafted graphene oxide nanosheets (GO-g-PTA) functioned as an antimicrobial agent and was used as filler for PCL-g-PAA nanofibers in the preparation of composite nanofiber mats, which exerted synergistic effects promoted by the antibacterial properties of GO-g-PTA and the hydrophilicity of PCL-g-PAA electrospun nanofibers. Thus, the composite nanofiber mats had antibacterial properties and absorbed body fluids in the wound healing process, thereby promoting cell proliferation. The biodegradation of the PCL-g-PAA electrospun nanofibers also demonstrated an encouraging result of three-fold weight reduction compared to the neat PCL nanofiber. Our findings may serve as guidelines for the fabrication of electrospun nanofiber composites that can be used mats for chronic wound care.

Nowadays, a dye-sensitized solar cell (DSSC) attracts attention to its development widely due to its several advantages, such as simple processes, low costs, and flexibility. In this work, we demonstrate the difference in device structures between small size and large size cells (5 cm × 5 cm, 10 cm × 10 cm and 10 cm × 15 cm). The design of the photoanode and dye-sensitized process plays important roles in affecting the cell efficiency and stability. The effects of the TiO2 electrode, using TiCl4(aq) pretreatment and post-treatment processes, are also discussed, whereas, the open-circuit voltage (Voc), short-circuit current density (Jsc), and module efficiency are successfully improved. Furthermore, the effects on module performances by some factors, such as dye solution concentration, dye soaking temperature, and electrolyte injection method are also investigated. We have demonstrated that the output power of a 5 cm × 5 cm DSSC module increases from 86.2 mW to 93.7 mW, and the module efficiency achieves an outstanding performance of 9.79%. Furthermore, enlarging the DSSC modules to two sizes (10 cm × 10 cm and 10 cm × 15 cm) and comparing the performance with different module designs (C-DSSC and S-DSSC) also provides the specific application of polymer sealing and preparing high-efficiency large-area DSSC modules.

Synthetic organic chemists endeavor to develop new reaction conditions, improve product yields, and enhance atom economy (synthetic methodologies), whereas the material scientists strive to create novel functional molecules/structures, increase device stabilities, and promote power conversion efficiencies via device engineering (organic optoelectronics). However, these two prominent research fields seem to have no intersections. Since joining national central university in 2012, our research philosophy aims to narrow, or rather to bridge the gap between synthetic methodologies and π-functional organic materials. In contrast to using multistep synthetic approaches based on Suzuki- or Stille coupling reactions, this personal account describes various step-saving and viable synthesis-shortcuts developed by our group, to access thiophene-based small molecules for optoelectronic applications. We expect these succinct and user-friendly alternative pathways designed by synthetic chemists would help material scientists to reach their target molecules in a more step-economical manner.

In most research papers, synthesis of organic hole-transporting materials relies on a key-reaction: Stille cross-couplings. This requires tedious prefunctionalizations including the preparation and treatment of unstable organolithium and toxicity-concern organotin reagents. In contrast to traditional multistep synthesis, this work describes that a series of star-shaped small molecules with a carbazole or phenothiazine core can be efficiently synthesized through a shortcut using optimized direct C-H/C-Br cross-couplings as the key step, thus avoiding dealing with the highly reactive organolithium or the toxic organotin species. Device fabrication of perovskite solar cells employing these molecules (6-13) as hole-transporting layers exhibit promising power conversion efficiencies of up to 17.57%.

Two polycyclic heteroarene derivatives, namely

Monitoring of vitamin B12 is important in the quality control of various pharmaceutical products. In this work, we design an ultrasensitive electrochemical sensor for the detection of vitamin B12 employing Pt modified Cu(HBTC)(4,4′-bipy)·3DMF (Pt = Platinum; DMF = N,N′-dimethylformamide; 4,4′-bipy = 4,4′-bipyridine; HBTC = 1,3,5-benzenetricarboxylic acid) electrode as an efficient electrocatalyst. The copper (Cu) complex nanorods were synthesised by solvothermal method and characterised by different surface analytical techniques. Cyclic voltammetric analysis reveals that the modified electrode shows excellent electrocatalytic redox reversibility towards Co3+/Co2+ redox couple at −0.192 and -0.268 V (vs. Ag/AgCl) with a sensitivity of 0.104 µA µM−1, a low detection limit of 50 nM, a signal-to-noise ratio of 3 and a wide linear range of 0.1–188.2 µM. The novelty of the system is that both oxidation and reduction currents Co3+/Co2+ redox couple has been used for the calibration curve so that the analytical errors during the course of analysis would be minimised. The enhanced electrocatalytic ability of the material has enabled discrimination of vitamin B12 from potential interfering species. The fabricated electrode was applied for the detection of vitamin B12 in two commercial pharmaceutical tablets and the results were found to be satisfactory.

Mixture of anti-solvents plays a decisive factor on the preparation of active layers for perovskite photovoltaic applications. This work explores the perovskite precursor treatment with various mixture of anti-solvents, in which it, not only improves in the surface morphology, but also enhances the crystallinity of the CH3NH3PbI3active layer. The toluene mixed with dichlorobenzene in a volume ratio of 1:1 has the best power conversion efficiency of 18.01%. It is also observed that adding certain amount of [6,6]-phenyl-C61-butyric acid methyl ester into the anti-solvent mixture can significantly improve the PCE of PSC by 6%, enhancing the passivation of grain boundary. Moreover, such procedure uses in p-i-n plane perovskite solar cell preparation is applicable to n-i-p stacking mesoporous perovskite solar cell. These perovskite active layer, prepare via this approach, are highly crystalline as well as homogeneous in nature with appropriate grain boundaries.

Low-cost and solution-processed perovskite solar cells have shown great potential for scaling-up mass production. In comparison with the spin coating process for fabricating devices with small areas, the blade coating process is a facile technique for preparing uniform films with large areas. High-efficiency perovskite solar cells have been reported using blade coating, but they were fabricated using the toxic solvent N,N-dimethylformide (DMF) in nitrogen. In this work, we present highly efficient blade-coated perovskite solar cells prepared using a green solvent mixture of γ-butyrolactone (GBL) and dimethyl sulfoxide (DMSO) in an ambient environment. By carefully controlling the interface, morphology, and crystallinity of perovskite films through composition variations and additives, a high power conversion efficiency of 17.02% is achieved in air with 42.4% reduction of standard deviation in performance. The findings in this work resolve the issues of scalability and solvent toxicity; thus, the mass production of perovskite solar cells becomes feasible.

Previously, benzotrithiophene (BTT)-based hole-transporting materials (HTMs) had to be doped with three chemical agents for high-efficiency perovskite solar cells (PSC). This work describes significant progress by which the first dopant-free BTT core-based HTM (YKP03) with EDOT spacers was readily accessed by step-saving direct C–H arylation. PSCs with dopant-free YKP03 showed promising efficiencies of up to 16.15% with potential long-term storage stability.

A new spirobifluorene-based hole-transporting material (spiro-tBuBED) was efficiently synthesized on the gram scale via straightforward C–H activations/arylations. Perovskite solar cells with spiro-tBuBED showed a promising power conversion efficiency of 18.6% without a device oxidation process previously considered to be indispensable.

New starburst small molecules bearing carbazole end-groups are step-economically synthesized in good isolated yields (70–84%) by sequential C–H activation/arylation reactions. Perovskite solar cells employing these molecules (YC05–08) as hole-transporting materials (HTMs) display a promising power conversion efficiency of up to 17.4%.

Perovskite solar cells (PSCs) have become one of the most promising renewable energy converting devices. However, in order to reach a sufficiently high power conversion efficiency (PCE), the PSCs typically require a high-temperature sintering process to prepare mesostructured TiO

A dual-layer fluorine-doped tin oxide (FTO) film has been fabricated by means of sequential spray pyrolysis for high-efficiency perovskite solar cells (PSCs). The H-FTO/L-FTO dual layer film consists of a H-FTO layer prepared at high deposition temperature (≈450 °C) and a L-FTO layer, fabricated at low deposition temperature (≈150 °C), which is used to replace the traditional compact TiO2 /FTO layer. The effects of F/Sn molar ratio, precursor solution concentration, and deposition temperature on the electrical, optical, surface morphological, and grain structural characteristics of H-FTO layers have been studied systematically. With an increase in precursor solution concentration, the mobility and carrier concentration of H-FTO increases; however, the grain size and sheet resistance decreases as the precursor solution concentration increases. A high deposition temperature results in a large grain size and enhanced haze value. The L-FTO layer expresses compact layer growth, inconsistent with the H-FTO surface structure, and possesses excellent electron collection and transport efficiency. The effect of the hole-blocking characteristics of L-FTO on the PSC performance is studied. This study provides a novel dual-layer FTO film to replace the traditional compact TiO2 /FTO layer, which is usually prepared by coating TiO2 precursor on FTO following calcination at 450 °C. The H-FTO/L-FTO dual-layer film can simplify the fabrication process and maintain a high power conversion efficiency (PCE); this results in more efficient electron transportation and blocking of holes. The champion device of PSCs with H-FTO/L-FTO shows the highest PCE of 17.37 % under the illumination of 100 mW cm-2 (AM1.5G).

Lead halide perovskite-structured solar cells (PSCs) have drawn great attention due to a rapid improvement in their photoelectric conversion efficiency in recent years. In this study, we have enhanced photovoltaic performance by using mesoscopic zinc-doped TiO2 (meso-Zn:TiO2) as the electron extraction layer. Zn:TiO2 nanoparticles (Zn:TiO2 NPs) with various zinc doping levels were synthesized by combining sol–gel and hydrothermal methods. The synthesized Zn:TiO2 NPs were used to fabricate electron extraction layers by a screen-printing method. We systematically investigated the surface morphology, crystal structure, contact angle, charge carrier dynamics, electron mobility, and electrical conductivity of various meso-Zn:TiO2. Furthermore, photo-assisted Kelvin probe force microscopy (KPFM) was used to analyze the surface potential of perovskite films coated with various meso-Zn:TiO2 to understand the electron extraction behavior under the illumination of light at various wavelengths. Moreover, the energy levels of various meso-Zn:TiO2 were estimated by ultraviolet photoelectron spectroscopy (UPS) and UV-vis absorption spectroscopy. We discovered that the 5.0 mol% meso-Zn:TiO2 exhibited the optimal band alignment with perovskite. Finally, the average power conversion efficiency (PCE) of PSCs with meso-Zn:TiO2 was enhanced from 13.1 to 16.8%, and such fabricated PSC yielded a champion PCE of 18.3%.

Anti-solvents play a critical role on the preparation of perovskite active layers for photovoltaic applications. This work explores the treatment of various anti-solvents for adjusting the crystallinity and morphology of perovskite active layer. It is found that the anti-solvent with a low dielectric constant and dipole moment is the most suitable one for the preparation of perovskite layer. It is also noted that the optimal volume ratio of the perovskite precursor to toluene as an anti-solvent is 1:3. Using toluene as the anti-solvent, the perovskite solar cells (p-i-n type) are fabricated with a single cell and a sub-module within an active area of 0.10 cm 2 and 11.25 cm 2 , respectively. Such display exhibits impressive power conversion efficiencies (PCE) of 13.12% and 11.60% with negligible J-V hysteresis, respectively, under the illumination of 100 mW/cm 2 (AM1.5G).

Comprehensive studies were carried out to explore the thickness-dependent characteristics of thermally evaporated C 60 thin films. The structural, optical, electronic and surface properties of the resultant C 60 thin films were analyzed using Raman scattering spectrometry, photoluminescence spectroscopy, absorbance spectroscopy, photoelectron emission spectrometry and water droplet contact angle measurement. The experimental results show that the thickness of the C 60 thin film has a decisive impact on the photovoltaic performance of CH 3 NH 3 PbI 3 based solar cells in terms of open-circuit voltage (V OC ), short-circuit current density (J SC ) and fill factor (FF). In the case of the 2.5 nm-thick C 60 film, the solar cells have the better V OC and J SC , as the results of the lower electron affinity and higher transparency. The FF of the solar cell is related to the coverage of C 60 on the transparent conductive electrode (TCE) and the CH 3 NH 3 PbI 3 perovskite continuity. Consequently, the photovoltaic performance can be expected to be improved by using a smooth TCE.

Recently, a hybrid perovskite material, ABX3 (A= Cs, CH3NH3, NH2CHNH2; B= Pb, Sn; X= Cl, Br, I), has received much attention as an active layer in new-generation solar cells. This material is usually fabricated with either a one-step or a two step process in solution. However, the surface morphology, nucleation rate and grain growth rate of the CH3NH3PbI3 perovskite light absorber prepared by the solution reaction process (SRP) are hard to control. Here, we show a fast solid-solid reaction process (SSRP), to fabricate ultraflat (roughness of approximately 12 nm) CH3NH3PbI3 perovskite thin films with large grain sizes (~947 nm). The SSRP simply involves directly contacting a lead iodide thin film (PbI2) with methylammonium iodide powder (CH3NH3I) without any chemical reagents at 120°C under a normal atmospheric environment. The SSRP reaction dynamics is investigated by an in situ heating scanning electron microscope (SEM) system. This innovative SSRP is an easy approach for the large-scale fabrication of planar heterojunction perovskite solar cells and allows us to demonstrate a power conversion efficiency of approximately 15.27% (active area of 0.16 cm2).