Electron Transfer Materials Research Articles

Semiconductor heterojunctions coated with reduced graphite oxide as electron transfer materials for high-performance perovskite solar cells

Exploring and insight into the relationship between the microstructure, light absorption performance, and carrier transport of perovskite light absorption layer materials and carrier transport layer materials is crucial for obtaining efficient and stable perovskite solar cells. We adopted a simple strategy to prepare a composite material known as reduced graphene oxide wrapped mesoporous hierarchical TiO2–CdS semiconductor heterojunctions (TiO2–CdS-RGO) as the electron transport layer in formamidine lead iodide perovskite solar cells. Compared with single TiO2 and binary composite, this composite material exhibits enhanced photoluminescence quenching, reduced photo generated carrier recombination rate, and improved electron transfer capability. Photovoltaic devices based on TiO2–CdS-RGO composite material showed a 14.5 % increase in short-circuit current density (JSC) and a 36.3 % increase in photoelectric conversion efficiency (PCE) compared to those with only TiO2. The improved optoelectronic properties observed with the TiO2–CdS-RGO as electron transfer layers can be attributed to several factors. On the one hand, mesoporous TiO2 with a high specific surface area is beneficial for perovskite infiltration and enhances electron transfer rate. On the other hand, the well-matching energy level structure among the three components aids in electrons extraction and reduces the recombination rate of photo generated charge carriers; In addition, RGO nanosheets with high conductivity serve as an efficient electron transfer network, providing a rapid charge transfer pathways, which is crucial for enhancing the photoelectric conversion performance of perovskite solar cells.

Calotropis-mediated biosynthesis of TiO2@SnO2/Ag nanocomposites for efficient perovskite photovoltaics

In this study, green SnO2@TiO2 nanocomposites were initially synthesized using an extract from the Calotropis plant as an electron transfer material for fabricating perovskite solar cells (PSCs). Further, plasmon impregnation (Ag-NPs) into the SnO2@TiO2 nanocomposites yielded nanocomposite (TiO2@SnO2/Ag) films. The effect of doping silver into the SnO2@TiO2 nanocomposites was investigated in detail to gain insights into how it influences the photovoltaic performance of the PSC. It resulted in enhanced quenching of photoluminescence compared to TiO2 and TiO2@SnO2 electron transport layers (ETLs), indicating faster charge extraction. PSCs utilizing the TiO2@SnO2/Ag ETL showed significantly improved performance with a power conversion efficiency of 22.2 %, a higher fill factor, and reduced hysteresis compared to cells with TiO2 and TiO2@SnO2 ETLs. The characterization of the nanocomposites revealed that the TiO2@SnO2/Ag ETL led to perovskite films with improved crystallinity, morphology, charge separation, and transfer properties. Electrochemical impedance spectroscopy confirmed the TiO2@SnO2/Ag ETL facilitated faster charge transfer and lower recombination at interfaces. Finally, the TiO2@SnO2/Ag ETL-based devices exhibited superior long-term stability in air, maintaining over 87 % of their initial efficiency. This work demonstrates that the incorporation of TiO2@SnO2/Ag nanocomposites is effective for developing high-performance and stable PSCs.

Hybrid Organic-Inorganic ZnO/PCBM Electron Transport Layer with Organic Lead Halide Perovskite Solar Cell Materials CH3NH3PbIX2, X is Cl or I

An experimental investigation has been undertaken to explore a variety of properties of organic perovskite solar cells (OPSCs) that are distinct in their photovoltaic response. In this study, OPSCs were constructed using zinc oxide, ZnO and [6,6]-phenylC[Formula: see text]-acid methyl ester, PCBM, as electron transfer materials (ETM), poly(3-hexylthiophene), P3HT, as hole transport material (HTM), and CH3NH3PbIX2 as a photosensitizer, where X is either Cl or I. The structural and optical characteristics of the ETM and HTM layers and the perovskite materials of OPSCs were investigated. The [Formula: see text]–[Formula: see text] and [Formula: see text]–[Formula: see text] curves of each solar cell prepared in OPSCs were measured using an integrated cell tester. This comprises a photovoltaic [Formula: see text]–[Formula: see text] measurement system and a solar simulation system. As a result of these results, the OPSC’s performance is evaluated. The calculations in this work suggest that the highest power conversion efficiency (PCE = 6.31%) was achieved in photovoltaic devices using CH3NH3PbI3 as the effective absorber layer and ZnO with PCBM as the ETM layer. At a light intensity of 100 mW/cm2, each OPSC cell was performed. Under the same conditions, the [Formula: see text]–[Formula: see text] curves were evaluated for each OPSC device. By improving the selection of organic and inorganic active materials in the ETM layer, OPSC performance may be improved.

Experimental and theoretical study of improved mesoporous titanium dioxide perovskite solar cell: The impact of modification with graphene oxide

The present study serves experimental and theoretical analyses in developing a hybrid advanced structure as a photolysis, which is based on electrospun Graphene Oxide-titanium dioxide (GO-TiO2) nanofibers as an electron transfer material (ETMs) functionalized for perovskite solar cell (PVSCs) with GO. The prepared ETMs were utilized for the synthesis of mixed-cation (FAPbI3)0.8(MAPbBr3)0.2. The effect of GO on TiO2 and their chemical structure, electronic and morphological characteristic were investigated and discussed. The elaborated device, namely ITO/Bl-TiO2/3 wt% GO-TiO2/(FAPbI3)0.8(MAPbBr3)0.2/spiro-MeTAD/Pt, displayed 20.14% disposition and conversion solar energy with fill factor (FF) of 1.176%, short circuit current density (Jsc) of 20.56 mA/cm2 and open circuit voltage (VOC) 0.912 V. The obtained efficiency is higher than titanium oxide (18.42%) and other prepared GO-TiO2 composite nanofibers based ETMs. The developed materials and device would facilitate elaboration of advanced functional materials and devices for energy storage applications.

MAPbBr3 Halide Perovskite-Based Resistive Random-Access Memories Using Electron Transport Layers for Long Endurance Cycles and Retention Time.

Recent studies have focused on exploring the potential of resistive random-access memory (ReRAM) utilizing halide perovskites as novel data storage devices. This interest stems from its notable attributes, including a high ON/OFF ratio, low operating voltages, and exceptional mechanical properties. Nevertheless, there have been reports indicating that memory systems utilizing halide perovskites encounter certain obstacles pertaining to their stability and dependability, mostly assessed through endurance and retention time. Moreover, the presence of these problems can potentially restrict their practical applicability. This study explores a resistive switching memory device utilizing MAPbBr3 perovskite, which demonstrates bipolar switching characteristics. The device fabrication procedure involves a low-temperature, all-solution process. For the purpose of enhancing the device's reliability, the utilization of TPBI(2,2',2″-(1,3,5-benzinetriyl)-tris(1-phenyl-1-H-benzimidazole) as an electron transfer material on the MAPbBr3 switching layer was implemented for the first time. The formation and rupture of Ag filaments in the MAPbBr3 perovskite switching layer are attributed to reduction-oxidation reactions. The TPBI is involved in the regulation of filaments during the SET and RESET processes. Hence, it can be shown that the MAPbBr3 device incorporating TPBI exhibited about 1000 endurance cycles when subjected to continuous voltage pulses. Moreover, the device consistently maintained ON/OFF ratios above 107. In contrast, the original MAPbBr3 device without TPBI demonstrated a significantly lower endurance with only 90 cycles observed. In addition, the MAPbBr3 device integrated with TPBI exhibited a retention time exceeding 3 × 103 s. The findings of this research provide compelling evidence to support the notion that electron transfer materials have promise for the development of halide perovskite memory systems owing to their favorable attributes of dependability and stability.

Theoretical analysis of OLED performances of some aromatic nitrogen-containing ligands.

It is well-known that tris(8-hydroxyquinoline) aluminum (Alq3) complex and N,N'diphenyl-N,N'-bis(3-methylphenyl)-1,1'-diphenyl-4,4'-diamine compound (TPD) are widely used as electron transfer material (ETL) and hole transfer material (HTL) in organic light emitting diode (OLED) structure, respectively. Considering the reference materials, in the present work, the OLED performances of some cyclic aromatic structures such as 4,4'azopyridine [AZPY], 4,4'-bipyridine [BIPY], 1,2-bis[4'-(4-methylphenyl)2,2':6'2″-terpyridin6-yl]ethyne (BISTERPY), 5,5'-diamino-2,2'-bipyridine (DABP), dipyrido[3,2-a:2',3'c]phenazine (DPP), 4,7-phenanthroline (PHEN) including nitrogen atom have been theoretically analyzed. It is important to note that B3LYP/6-31G(d) and B3LYP/TZP levels of the theory were taken into account for the calculations about monomeric and dimeric structures, respectively. Additionally, the calculations of the mentioned monomeric form were performed at B3LYP-D3/6-31G, CAM-B3LYP/6-31G and ωB97X-D/6-31G(d) levels. For a detailed theoretical analysis, the reorganization energies (λe and λh), adiabatic and vertical ionization potentials and electron affinities, the effective transfer integrals (Ve and Vh), and the charge transfer rates (We and Wh) of all compounds were computed by means of computational chemistry tools. In the light of calculated parameters, it is determined that these mentioned aromatic cyclic structures will be used in which layers of OLED structure. The results obtained in this study will be helpful in the design and applications of new molecules as OLED materials in the future.

Organic light‐emitting diode behaviors of some synthesized platinum(II)‐based complexes

AbstractOrganic light‐emitting light diodes (OLEDs) have been increasingly used in displays, replacing liquid‐crystal displays (LCD) and light‐emitting diodes (LEDs) panels. The increase in commercial use of OLED has led to the search for OLED with high performance. For that reason, the OLED properties of monomers and dimers of some synthesized platinum(II)‐based complexes were estimated by using different computational chemistry tools with different codes. The electron/hole reorganization energies, the adiabatic/vertical ionization potentials, the adiabatic/vertical electron affinities, the chemical hardness values, the dipole moments, the frontier orbital shapes/energy levels, the energy gaps, the emission wavelengths, spin‐orbit matrix elements, the rates of reverse intersystem crossing and intersystem crossing of the investigated complexes were determined. From the theoretically obtained data, it was found that Pt(hppz)2 and Pt(fppz)2 complexes can be used as electron transfer material. Furthermore, it was stated that Pt(f2bipz)(bpy) is both electron‐blocking layer and hole blocking layer materials. Moreover, it was noted that that PtOEP complex can be utilized as a good electron injection layer and hole injection layer material. Addition to these, it was emphasized that that Pt(f2bipz)(bpy) can be considered as a good candidate for near infrared organic light emitting diodes and thermal activated delayed fluorescent organic light emitting diodes. In light of computational chemistry, it should be expected that the study will provide a great contribution to studies related to organic light emitting diodes.

Improved photocatalytic decolorization of reactive black 5 dye through synthesis of graphene quantum dots-nitrogen-doped TiO2.

Graphene quantum dots (GQDs), a new solid-state electron transfer material was anchored to nitrogen-doped TiO2 via sol gel method. The introduction of GQDs effectively extended light absorption of TiO2 from UV to visible region. GQD-N-TiO2 demonstrated lower PL intensity at excitation wavelengths of 320 to 450nm confirming enhanced exciton lifespan. GQD-N-TiO2-300 revealed higher surface area (191.91m2g-1), pore diameter (1.94nm), TEM particle size distribution (4.88 ± 1.26nm) with lattice spacing of 0.45nm and bandgap (2.91eV). In addition, GQDs incorporation shifted XPS spectrum of Ti 2p to lower binding energy level (458.36eV), while substitution of oxygen sites in TiO2 lattice by carbon were confirmed through deconvolution of C 1s spectrum. Photocatalytic reaction followed the pseudo first order reaction and continuous reductions in apparent rate constant (Kapp) with incremental increase in RB5 concentration. Langmuir-Hinshelwood model showed surface reaction rate constants KC = 1.95mg L-1min-1 and KLH = 0.76 L mg-1. The active species trapping, and mechanism studies indicated the photocatalytic decolorization of RB5 through GQD-N-TiO2 was governed by type II heterojunction. Overall, the photodecolorization reactions were triggered by the formation of holes and reactive oxygen species. The presence of •OH, 1O2, and O2• during the photocatalytic process were confirmed through EPR analysis. The excellent photocatalytic decolorization of the synthesized nanocomposite against RB5 can be ascribed to the presence of GQDs in the TiO2 lattice that acted as excellent electron transporter and photosensitizer. This study provides a basis for using nonmetal, abundant, and benign materials like graphene quantum dots to enhance the TiO2 photocatalytic efficiency, opening new possibilities for environmental applications.

Small carbazole-based molecules as hole transporting materials for perovskite solar cells

In this study, six small carbazole-based molecules are investigated for usage as hole transport materials (HTMs) in perovskite solar cells. Among these compounds, two molecules based on 9-(4-(thiophen-2-yl)phenyl)-9H-carbazole thiophene-phenyle and carbazole (M1 and M2) were already synthesized, and four new molecules are designed by substituting carbazole, in positions 3,6 and 2,7, with methoxyphenyl (P1 and P2) and dimethoxyphenylamine (E1 and E2). Theoretical methods used in the calculations included density functional theory and time-dependent density functional theory. FMOs of all under-probe molecules are well positioned to ensure accurate alignment and prevent charge recombination at the perovskite material interface. The molecules' absorbance in the area below 404 nm shows that HTMs cannot compete with perovskite materials in an inverted configuration of a device. Reorganization energies indicate that M1, P1,2 and E1,2 are more favourable to be HTM, while M2 shows a favourable electron transfer; it can be used as an electron transfer material (ETM). The results demonstrate that hole-electron couples can easily separate for any under-exanimated molecules, simplifying hole transport and enhancing the short-circuit (JSC). Additionally, DMPA-based molecules (E1,2) may display chemical instability because of their poor hardness and the local distribution of charge in electrostatic potential maps.

Influence of phthalocyanine nanowire dye on the performance of titanium dioxide-metal organic framework nanocomposite for dye-sensitized solar cells

In clean energy, dye-sensitized solar cells (DSSCs) have become a key tool for the photovoltaic effect. Copper phthalocyanine nanowire (CuPcNW) dyes can be used in DSSCs to generate low-cost devices, light-harvesting, fast electron transfer materials, and prevent recombination processes, as well as improve conductivity. This study investigates the effect of CuPcNW dye on TiO2, MOF, and TiO2-MOF in photovoltaic performance. Electrochemical characterizations such as cyclic voltammetry and electrochemical impedance spectroscopy (EIS) have also revealed the half-wave peak potentials of the ternary nanocomposite with values of 0.44 and 0.35 V for the oxidation and reduction reversible reactions. The EIS behavior revealed the improved conductivity of the nanocomposite with a value of 244 µS/cm. It was seen that the TiO2-MOF/CuPcNW nanocomposite achieved a maximum power conversion efficiency of 6.467 % owing to the presence of CuPcNW, which improved the photocurrent density, faster electron transport, and reduced charge recombination in the nanocomposite.

The design of push-pull substituted coronene molecules for optoelectronic applications

The optoelectronic and electronic properties of coronene ([6]circulene) and push-pull coronene molecules were predicted by using different computational chemistry programs. For this aim, the electron/hole reorganization energies, the adiabatic/vertical ionization potentials, the adiabatic/vertical electron affinities, the chemical hardness values, the frontier orbital shapes and energy levels of the coronene and its derivatives were obtained at B3LYP/6-31G(d) level. Then the energies of the studied molecules in S0, S1, and T1 states were calculated at PBE0/TZP level. From the obtained results, the emission values and TADF parameters of the investigated compounds were determined. Based on the theoretically obtained results, it was found that 6ethynyl-coronene and 12ethynyl-coronene molecules can be used as electron transfer materials and 6cyano-coronene and 12cyano-coronene compounds can be utilized as hole transfer materials. Additionally, it was noted that 6NO2-coronene and 12NH2-coronene derivatives can be good candidates for electron blocking materials, while 6NH2-coronene and 12NH2-coronene molecules can be utilized as hole blocking materials. Furthermore, it was emphasized that both 6NH2-coronene and 12NH2-coronene molecules can be good candidates as both electron injection and hole injection materials. Lastly, it was reported that 6ethynyl-coronene and 12cyano-coronene structures can be considered the most suitable candidates for near infrared organic emitting diodes.

Wide distribution of extracellular electron transfer functionality in natural proteinaceous organic materials for microbial reductive dehalogenation.

Extracellular electron transfer materials (EETMs) in the environment, such as humic substances and biochar, are formed from the humification/heating of natural organic materials. However, the distribution of extracellular electron transfer (EET) functionality in fresh natural organic materials has not yet been explored. In the present study, we reveal the wide distribution of EET functionality in proteinaceous materials for the first time using an anaerobic pentachlorophenol dechlorinating consortium, whose activity depends on EETM. Out of 11 natural organic materials and 13 reference compounds, seven proteinaceous organic materials (albumin, beef, milk, pork, soybean, yolk, and bovine serum albumin) functioned as EETMs. Carbohydrates and lipids did not function as EETMs. Comparative spectroscopic analyses suggested that a β-sheet secondary structure was essential for proteins to function as EETMs, regardless of water solubility. A high content of reduced sulfur was potentially involved in EET functionality. Although proteinaceous materials have thus far been considered simply as nutrients, the wide distribution of EET functionality in these materials provides new insights into their impact on biogeochemical cycles. In addition, structural information on EET functionality can provide a scientific basis for the development of eco-friendly EETMs.

SnO2@ZnO nanocomposites doped polyaniline polymer for high performance of HTM-free perovskite solar cells and carbon-based

Herein, at first, green SnO2@ZnO nanocomposites were synthesized using Calotropis plant extract as an electron transfer material (ETM) to fabricate low-temperature-processed perovskite solar cells (PSCs). Then, the polyaniline (PANI) polymer was applied as an efficient additive to improve perovskite film quality. Under the effects of the small content of PANI additive, the quality of perovskite films is enhanced, which showed higher crystallinity in (110) crystal plane; also, the perovskite grains were found to be enlarged from 342 to 588 nm. The power conversion efficiency (PCE) of the prepared PSCs with SnO2@ZnO.PANI nanocomposites electron transfer layer (ETL) increased by 3.12%, compared with the PCE of SnO2@ZnO nanocomposites. The perovskite devices using SnO2@ZnO.PANI nanocomposites ETL have shown good stability during 480 h of tests. Furthermore, the optimal PSCs were fabricated by the mp-TiO2/SnO2@ZnO.PANI nanocomposites as ETL, which has a power conversion efficiency of 15.45%. We expect that these results will boost the development of low-temperature ETL, which is essential for the commercializing of high-performance, stable, and flexible perovskite solar cells.

The TiO2 films with sandwich-type polyoxometalates in dye sensitized solar cells with electron recombination decreasing and dye adsorption increasing

Unfavorable electron recombination, which hinders the efficiency of dye-sensitized solar cells (DSSCs), usually occurs at the TiO2/dye/electrolyte interface on a photoanode. Polyoxometalates (POMs), as good electron acceptors, can be used as electron-transfer materials in DSSCs to improve electron transport in TiO2 and reduce electron recombining on the interface of a photoanode. In this paper, the pure inorganic sandwich-type POM Na9[Na3(H2O)6Cu3(H2O)3(SbW9O33)2]·40H2O (Cu3Na3POM) was mixed with TiO2 to form nanocomposites by simple sol-gel method. X-ray photoelectron spectroscopy (XPS) proved that Cu3Na3POM and TiO2 combined. Then the nanocomposite was doped with P25 to form Cu3Na3POM@TiO2/P25 photoanodes which were applied to the DSSCs. The Cu3Na3POM improved the transfer and recombination of electrons in the photoanode, proved by open circuit voltage decay (OCVD) and electrochemical impedance spectroscopy (EIS). Scanning electron microscopy (SEM) and ultraviolet-visible (UV-vis) absorption spectra showed that Cu3Na3POM optimized the morphology of the photoanode and the adsorption capacity of dye. The electrochemical test showed that the photoelectric conversion efficiency of DSSCs with Cu3Na3POM@TiO2/P25 photoanodes was enhanced to 6.91%, which was 13.66% higher than the DSSCs without Cu3Na3POM.

Tailoring type-II all-in-one buried interface for 1.635V-voltage, all-inorganic CsPbBr3 perovskite solar cells

Precise manipulation on buried interface of perovskite film highly determines the photovoltaic performance of perovskite solar cells (PSCs). Herein, we demonstrate a SnO2-SnS2 heterojunction nanocrystal as an efficient electron transfer material to heal the defective interface for planar all-inorganic CsPbBr3 PSCs. Arising from the matched lattice distance of SnS2 with SnO2 and CsPbBr3, an all-in-one SnO2-SnS2-CsPbBr3 interface is fabricated, in which SnS2 plays a role of “bridge” to connect incompatible interface. Consequently, the charge recombination loss is minimized owing to the Type-II band alignment and epitaxial growth induced defect reduction, achieving a remarkable efficiency of 10.72% with a high open-circuit voltage of 1.635V. Considering the high tolerance to high humidity (80%) for 700 h and high temperature (80 °C) over 30 days, these preliminary results can provide a new perspective for the rational design of ideal charge transfer materials to improve the efficiency and stability of PSCs.

Activation of extracellular electron network in non-electroactive bacteria by Bombyx mori silk

Extracellular electron transfer material (EETM) has increasingly attracted attentions for the enhancing effect on multiple microbial reactions. Especially, EETM is known to be essential to activate the energy network in non-electroactive bacteria. It is motivated to find out an EETM which is natural-based, environmentally friendly, and easily produced at large-scale. In this study, Bombyx mori silk is found, for the first time, to function as an EETM by using an EETM-dependent pentachlorophenol (PCP) dechlorinating anaerobic microbial culture. Subsequently, by dividing fibroin fiber into different soluble/insoluble fractions and correlating their EET functions with their structural properties based on various spectroscopic analyses, the β-sheet configuration is suggested as an essential structure supporting the EET function of silk materials. The analyses also suggested the involvement of sulfur-containing amino acids in this function. The EET function is not degraded by boiling or acid/alkaline treatments and the material can be utilized multiple times, although it is susceptible to UV irradiation. Bombyx mori silk also enhance other microbial reactions, including Fe(III)OOH reduction, CO2 reduction to acetate, and nitrogen fixation. This discovery provides a basis for developing biotechnology for environmental remediation, global warming reduction, and biofertilizer production using Bombyx mori silk and its wastes.

Single-Layered MXene Nanosheets Doping TiO2 for Efficient and Stable Double Perovskite Solar Cells.

The inorganic lead-free Cs2AgBiBr6 double perovskite structure is the promising development direction in perovskite solar cells (PSCs) to solve the problem of the instability of the APbX3 structure and lead toxicity. However, the low short-circuit current and power conversion efficiency (PCE) caused by the low crystallization of Cs2AgBiBr6 greatly limit the optoelectronic application. Herein, we adopt a simple strategy to dope single-layered MXene nanosheets into titania (Ti3C2Tx@TiO2) as a multifunctional electron transport layer for stable and efficient Cs2AgBiBr6 double PSCs. The single-layered MXene nanosheets significantly improve the electrical conductivity and electron extraction rate of TiO2; meanwhile, the single-layered MXene nanosheets change the surface wettability of the electron transport layer and promote the crystallization of the Cs2AgBiBr6 double perovskite in solar cell devices. Therefore, the PCE went up by more than 40% to 2.81% compared to that of a TiO2 based device, and the hysteresis was greatly suppressed. Furthermore, the device based on Ti3C2Tx@TiO2 showed the long-term operating stability. After storing the device for 15 days under ambient air conditions, the PCE still remained a retention rate of 93% of the initial one. Our finding demonstrates the potential of Ti3C2Tx@TiO2 in electron transfer material of high-performance double PSCs.

Exploring the electron-hole transport nature and optoelectronic properties of 4-nitro-4′-amino-azobenzene-based dyes

Charge transport and electronic properties of 4-nitro-4′-amino-azobenzene compounds with donor-acceptor backbone were examined at the molecular level. Optical properties of all the studied six azobenzene dyes were also explored at the solid-state bulk level, i.e., dielectric constants, conductivity, refractive index, and extinction coefficient values. The introduction of benzyl group enhances whereas propanenitrile diminishes the values for real and imaginary dielectric functions. Moreover, the substitution of 3-methoxy-3-oxopropyl and propanenitrile at amino group decreases the real conductivity values; however, bis(3-methoxy-3-oxopropyl) improves these values. These 4-nitro-4′-amino-azobenzene compounds showed good refractive indices in the energy range 0–2 eV which revealed that these dyes would be efficient to generate healthier outputs with lower energy inputs. The effect of substituents was also investigated on transfer integrals, frontier molecular orbitals (FMOs), reorganization energies, electron affinity (EA), and ionization energy (IE). The ground-state geometries were optimized by density functional theory at B3LYP/6-31G** level to probe the molecular level properties. The same level of theory was used for the cation and anion optimizations. The hole and electron transfer nature of azo dyes was investigated by evaluating the electron/hole transfer integrals (Velectron/Vhole) as well as hole and electron reorganization energy values. The results exposed that superior Vhole values of Azo2 and Azo4 might lead to these dyes as p-type contenders. Moreover, larger Velectron values of Azo1, Azo3, Azo5, and Azo6 might lead to these dyes as n-type competitors. These results revealed that inspected Azo dyes would be able to serve as competent hole and electron transfer materials within versatile organic semiconductors.

Size controlled synthesis of gadolinium doped titanium dioxide nanoparticles by low temperature hydrothermal method towards effective photovoltaic application

In the present study, Pure and (1 wt% and 4 wt%) Gadolinium (Gd3+) doped TiO2 nanoparticles were developed with a hydrothermal method, and dye sensitized solar cells were fabricated using them as an electron transfer material. The anatase phase and structural property of pure and Gd3+ doped TiO2 nanoparticles were examined using XRD analysis. Energy Dispersive X-ray analysis (EDAX) confirmed the presence of titania nanoparticles and UV–Vis absorption spectroscopy was used for the investigation of the optical properties of synthesized photocatalysts. The photovoltaic performance of Gd3+:TiO2 based solar cells is improved compared to un-doped TiO2 based solar cell. The power conversion efficiency of the solar cells on Gd3+:TiO2 increased to 4.88%, which is higher than that of the solar cells based on un-doped TiO2.

Synthesis and fluorescence properties of two dendritic molecules based on naphthalimide and triphenylamine.

Artificial light-harvesting systems have attracted great interest in biological photosynthesis and photo-voltaic devices areas due to their unique structures, easy purification, low-cost, and convenient processing abilities. Here, two dendritic molecules based on triphenylamine and naphthalimide have been designed and synthesized, their structures were confirmed by 1 H NMR, ESI-MS, and high resolution mass spectrometry. In these molecules, triphenylamine units perform as the electron donor moiety, and naphthalimide units perform as the electron acceptor. The obvious quenched fluorescence intensity and considerably shortened lifetime of the dendritic molecules combined with the molecular frontier orbital energy levels proved that the dendritic molecules not only are good candidates as hole-transporting materials but also are two excellent photo-induced electron transfer materials. Therefore, it is believed that these dendritic molecules have potential application value in photo-voltaic devices.