Gap EG Research Articles

Screened optimally tuned range separated hybrid functional for solvated low bandgap molecular systems.

The description of electronic properties of low bandgap molecular system is often performed by using density functional theory (DFT) and time dependent (TD) DFT calculations with the optimally tuned range-separated hybrid (OT-RSH) functional, as it contains the necessary ingredients to reliably predict charge transfer excitations. However, the range separating parameter (ω) is system-dependent and its optimization, including the chemical environment, is intricate. Refaely-Abramson et al. demonstrated that the gap renormalization in molecular crystals, a ground state property, can be represented by an OT-RSH functional screened by ɛstatic [Phys. Rev. B 88, 081204(R) (2013)], the zero frequency scalar dielectric constant. In this study, we propose the use of an OT-RSH functional screened by the scalar dielectric constant in the high frequency limit (OT-sRSH), ɛ∞, an appropriate constraint for vertical ionization energies or excitations in a dielectric environment. We have performed calculations for S,N-heteroacene derivatives in tetrahydrofuran and dichloromethane. The "unscreened" OT-RSH functional tends to underestimate experimental ionization potentials (IPs) and optical gaps (Egs) by up to 1.5 and 0.5eV, respectively. In contrast, OT-sRSH functional calculations underestimate IPs and Egs by only 0.4 and 0.2eV. We also compared the OT-sRSH results to explicitly solvated OT-RSH functional calculations for oligothiophenes in dioxane, benzene in ammonia, and methylene blue in water. We observe that both the approaches perform similarly for weakly interacting intermolecular systems and deviate for solvent-solute interacting systems, as expected. In conclusion, the OT-sRSH functional can describe molecular systems with environmental polarization effects accurately, a step toward describing realistic molecular systems.

Optoelectronic Properties of Cold Plasma-Deposited, Oxidized Sn-C Thin Films.

We report on investigating the structural and electronic properties of semiconducting and insulating layers produced in a process resembling percolation in a unique cold plasma fabrication method (plasma-enhanced chemical vapor deposition-PECVD). Amorphous carbon-tin films (Sn-C) produced from tetramethyl tin (TMT) with an acoustic-frequency glow discharge in a three-electrode reactor were investigated. The layers, after air exposure, oxidized to SnO2/Sn-C. Depending on the coupling capacitance applied to the plasma reactor, the films could be obtained in the form of an amorphous semiconductor or an amorphous insulator. We assume that the semiconductor consists of an internal network of channels auto-organized during deposition. The insulator does not demonstrate any internal structure features. An investigation on conductive filaments creating low-dimensional (LD) nanojunctions in the semiconductor and the location of energetic levels in the insulator was performed. The main parameters of the electronic band structure of the insulating film, such as the transport gap EG (5.2 eV), optical gap Eopt (3.1 eV), electron affinity Χ (2.1 eV), and ionization potential J (7.3 eV), were determined. We have demonstrated a simple approach for developing a catalyst candidate consisting of amorphous semiconductor-insulator nanojunctions for (photo)catalytic hydrogen evolution or CO2 reduction.

Asymmetric Fluorene‐Based Fused‐Ring Molecules Acceptors for Fullerene‐Free Organic Solar Cells

Asymmetric fluorene‐based fused‐ring molecules acceptors 2,2′‐((2Z,2′Z)‐(((11,11‐dioctyl‐5,5‐dioxido‐11H‐benzo[b]fluoreno[2,3‐d]thiophene‐3,9‐diyl)bis(3‐octylthiophene‐5,2‐diyl))‐bis(methaneylylidene))bis(3‐oxo‐2,3‐dihydro‐1H‐indene‐2,1‐diylidene))dimalononitrile [BTOFIC] and 2,2′‐((2Z,2′Z)‐((5,5′‐(11,11‐dioctyl‐11H‐benzo[b]fluoreno[2,3‐d]thiophene‐3,9‐diyl)bis(3‐octylthiophene‐5,2‐diyl))bis(methanylylidene))‐bis(3‐oxo‐2,3‐dihydro‐1H‐indene‐2,1‐diyl‐idene))dimalononitrile [BTFIC] are synthesized. BTOFIC and BTFIC are easily soluble in common organic solvents. The highest occupied molecular orbital energy levels, the lowest unoccupied molecular orbital energy levels, and the bandgaps (Egs) of BTOFIC and BTFIC are −5.91, −3.87, and 2.04 eV and −5.72, −3.81, and 1.91 eV, respectively. BTOFIC and BTFIC show the maximum absorption peak (λmax) at 548 and 648 nm and a strong shoulder peak at 592 and 576 nm in film, and the optical bandgaps of 1.87 and 1.81 eV, respectively. The organic solar cells (OSCs) fabricated with poly[4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)benzo[1,2‐b;4,5‐b′]dithiophene‐2,6‐diyl‐alt‐(4‐(2‐ethylhexyl)‐3‐fluorothieno[3,4‐b]thiophene‐)‐2‐carboxylate‐2‐6‐diyl)] [PTB7‐Th]:BTOFIC and PTB7‐Th:BTFIC show a power conversion efficiency of 3.31% and 5.35%, respectively. In this research, it is revealed that BTOFIC and BTFIC can be potential asymmetric non‐fullerene acceptors for further development of OSCs.

Regioregular Pyridal[1,2,3]Triazole‐Based Polymer Semiconductors for High Mobility and Near‐Infrared Light Emission Applications

AbstractThe development of polymer semiconductors with strong luminescence and high mobility has always been challenging, and achieving both properties together is considered paradoxical according to molecular design principles. Studies on novel molecular species with unique optoelectrical characteristics are limited. Herein, a novel fully rigid coplanar thiophene‐pyridal[1,2,3]triazole‐thiophene (T‐PT‐T) class structure with considerable intramolecular noncovalent interactions is proposed. To balance luminescence and carrier transport properties, a series of non‐conventional regioregular conjugated polymers (PPTs) with suitable energy gaps (Egs ≈ 1.8 eV) are developed, which exhibit near‐infrared (NIR, 700–1000 nm) light emission and high mobility. One of the synthesized polymers, PPT‐2, exhibits an excellent photoluminescence quantum yield (PLQY) of 9% in the solid‐state and a high mobility reaching 0.35 cm2 V−1 s−1, indicating superior performance compared to other NIR light‐emitting polymer semiconductors. The authors believe that the class structure of fully rigid coplanar “T‐PT‐T” could be harnessed to develop high‐mobility NIR light‐emitting polymer semiconductors.

Use of ultrasound-assisted co-precipitation route to obtain CuMnO2 semiconductor nanomaterials

CuMnO2 nanoparticles were obtained for the first time by sonochemical synthesis in an aqueous solution of sodium hydroxide containing soluble copper and manganese nitrate reactants without any further thermal treatment. Experiments were performed at different lengths of time (20 min, 30 and 40 min) and ultrasound amplitude of 80%. The materials present the expected crednerite structure (C2/m space group), and the nanoparticles average size and morphology for each sample are studied by nanoparticle tracking analysis method, respectively, by transmission electron microscopy. The as-obtained materials display p-type semiconductivity behavior at room temperature and the value for direct optical band gap EG is estimated to be approximately ~ 3.6 eV. The study of the magnetic properties for the nanocrystalline crednerite samples reveals 2D magnetic behavior below 110 K and a weak ferromagnetic component at ~ 20 K.

Effect of the paramagnetic to spin-glass phase transition on the fundamental absorption edge of MnIn2Se4 magnetic semiconducting compound

The temperature dependence of the indirect and direct fundamental band gaps of the layered compound MnIn2Se4,that crystallizes in a rhombohedral defect structure with space group R -3m (D5/3d), was studied by optical absorption spectra. The data were analyzedin terms of current theoretical models that take into account the contribution of antiferromagnetic exchange interaction between spins to the shift of the energy gap EG with T in the vicinity of the critical paramagnetic to spin-glass phase transition. It was established that short- and long-range effect spin correlations dominate the contribution to this shift in the critical region below about 20 K, near the spin-glass freezing temperature Tf, and noncritical one, between about 70 and 160 K, far from Tf, respectively. An intermediate temperature region, compatible with the behaviour expected for a cluster-glass transition where a gradual freezing of the magnetic moments occurs, was also observed.

Thiophene and thieno[3,2-b]thiophene π-bridged pyrrolo[3,4-c]pyrrole-1,3-dione-based wide band-gap polymers for fullerene and non-fullerene organic solar cells

Abstract The conventional polymerization of 2,5-bis(trimethylstannyl)thiophene (T) or 2,5-bis(trimethylstannyl)thieno[3,2-b]thiophene (Tt) with 4,6-bis(5-bromothiophen-2-yl)-5-octyl-2-(2-octyldodecyl)pyrrolo[3,4-c]pyrrole-1,3(2H,5H)-dione (TPPDT) afforded new alternating polymers, namely P(T-TPPDT) or P(Tt-TPPDT), respectively. Both P(T-TPPDT) and P(Tt-TPPDT) exhibited similar thermal stabilities (5% weight loss at around 420 °C) and absorption maxima (λmax ≈ 515 nm) as films. The absorption bands of P(T-TPPDT) and P(Tt-TPPDT) extend between 300 and 620 nm, with optical band gaps (Egs) of 2.02 eV and 2.00 eV, respectively. The highest-occupied/lowest-unoccupied molecular-orbital energies of P(Tt-TPPDT) (HOMO/LUMO: −5.35 eV/–3.33 eV) were found to be somewhat higher than those of P(T-TPPDT) (HOMO/LUMO: −5.31 eV/–3.31 eV). Organic solar cells (OSCs) prepared using 1:1.5 (w/w) P(T-TPPDT):PC70BM or P(Tt-TPPDT):PC70BM (PC70BM = [6,6]-phenyl C70 butyric acid methyl ester) blends provided power-conversion efficiencies (PCEs) of 3.50% or 4.71%, respectively. On the other hand, OSCs prepared with 1:1 (w/w) P(T-TPPDT):ITIC or P(Tt-TPPDT):ITIC (ITIC = 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)indanone))-5,5,11,11-tetrakis(4-hexylphenyl)dithieno[2,3-d:2′,3′-d’]-s-indaceno[1,2-b:5,6-b’]dithiophene) blends exhibited improved PCEs of 5.32% or 6.35%, respectively.

Te-doped perovskite NaTaO3 as a promising photocatalytic material for hydrogen production from water splitting driven by visible light

The photocatalytic hydrogen production from water splitting can be achieved by using the pristine NaTaO3 experimentally, but the reaction cannot be driven by the visible light because of the wide band gap of NaTaO3. The present work focuses on tuning the photocatalytic performance of NaTaO3 into the visible light range by doping S, Se, and Te elements. The obvious decrease in band energy gaps (Egs) and noticeable red-shift of the absorption edges are observed for the doped structures. The valence band maximum and conduction band minimum of the doped structures satisfy the requirement of the water splitting. Moreover, a significant enhancement of absorption coefficient in the visible light range is observed for the doped structure of Te@O. The calculated carrier mobility is used to evaluate the charge spatial separation of Te@O and the unusual increases and the obvious differences of the mobility of the electrons and holes are observed.

Graphene-insulator-semiconductor capacitors as superior test structures for photoelectric determination of semiconductor devices band diagrams

We report on the advantages of using Graphene-Insulator-Semiconductor (GIS) instead of Metal-Insulator-Semiconductor (MIS) structures in reliable and precise photoelectric determination of the band alignment at the semiconductor-insulator interface and of the insulator band gap determination. Due to the high transparency to light of the graphene gate in GIS structures large photocurrents due to emission of both electrons and holes from the substrate and negligible photocurrents due to emission of carriers from the gate can be obtained, which allows reliable determination of barrier heights for both electrons, Ee and holes, Eh from the semiconductor substrate. Knowing the values of both Ee and Eh allows direct determination of the insulator band gap EG(I). Photoelectric measurements were made of a series of Graphene-SiO2-Si structures and an example is shown of the results obtained in sequential measurements of the same structure giving the following barrier height values: Ee = 4.34 ± 0.01 eV and Eh = 4.70 ± 0.03 eV. Based on this result and results obtained for other structures in the series we conservatively estimate the maximum uncertainty of both barrier heights estimations at ± 0.05 eV. This sets the SiO2 band gap estimation at EG(I) = 7.92 ± 0.1 eV. It is shown that widely different SiO2 band gap values were found by research groups using various determination methods. We hypothesize that these differences are due to different sensitivities of measurement methods used to the existence of the SiO2 valence band tail.

Electronic structure of phosphorene nanoflakes. A theoretical insight

Abstract Phosphorene nanoflakes of different shapes and sizes were studied at the hybrid BHandHLYP level of theory. This functional accurately reproduces the experimental bond lengths and valence angles of black phosphorus. All nanoflakes were found to have a singlet ground state and their band gaps (Egs) decrease linearly with 1/N, where N is the number of P atoms in the nanoflakes. It seems that the topology of the nanoflake edges does not affect Eg. The ionization potentials (IPs) and electron affinities (EAs) generally grow smaller with increasing nanoflake size. The change in IPs and EAs with size correlate with the delocalization pattern of polaron cations and anions. The shape and nature or the longest edge (zig-zag or armchair) affect both the IP and EA. Nanoflakes with a long zigzag edge have higher IPs and lower EAs compared to square systems. Low theoretically calculated hole reorganization energies (less than 0.1 eV) are in agreement with the experimentally determined high hole mobility in phosphorene. The low hole reorganization energies are due to the better ability of phosphorene nanoflakes to delocalize polaron cations compared to polaron anions.

Synthesis of Water-Soluble Antimony Sulfide Quantum Dots and Their Photoelectric Properties

Antimony sulfide (Sb2S3) has been applied in photoelectric devices for a long time. However, there was lack of information about Sb2S3 quantum dots (QDs) because of the synthesis difficulties. To fill this vacancy, water-soluble Sb2S3 QDs were prepared by hot injection using hexadecyltrimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS) mixture as anionic-cationic surfactant, alkanol amide (DEA) as stabilizer, and ethylenediaminetetraacetic acid (EDTA) as dispersant. Photoelectric properties including absorbing and emission were characterized by UV-Vis-IR spectrophotometer and photoluminescence (PL) spectroscopic technique. An intensive PL emission at 880 nm was found, indicating Sb2S3 QDs have good prospects in near-infrared LED and near-infrared laser application. Sb2S3 QD thin films were prepared by self-assembly growth and then annealed in argon or selenium vapor. Their band gaps (Egs) were calculated according to transmittance spectra. The Eg of Sb2S3 QD thin film has been found to be tunable from 1.82 to 1.09 eV via annealing or selenylation, demonstrating the good prospects in photovoltaic application.

Design Parameters for Phase‐Change Materials for Nanostructure Resonance Tuning

Phase‐change materials (PCMs) are a promising platform for programmable metamaterials in the infrared (IR) spectral range. This is based on the large refractive index change between the amorphous and crystalline phases of PCMs accompanied by their low dielectric losses in the IR. These PCMs can exist in various stoichiometries, leading to distinct changes in dielectric properties which can be exploited for resonance tuning. To investigate these differences, nanoantennas with thin films of three (GeTe)x–(Sb2Te3)1−x compounds such as Ge2Sb2Te5 (GST‐225), Ge3Sb2Te6 (GST‐326), and Ge8Sb2Te11 (GST‐8211) are combined. Different PCM stoichiometries regarding their suitability for resonance tuning are systematically compared for the first time and the PCM GST‐8211 is introduced into the field of photonics. An increase of the antenna resonance frequency shift based on an increasing GeTe content in the compound is experimentally demonstrated. This leads to the largest figure of merit for antenna resonance tuning in the IR using PCMs reported so far. Based on the insights obtained, the changes in the real part of the permittivity Δε1, the band gap EG, and the charge carrier concentration N are identified as design parameters for resonance tuning with PCMs.

Ballistic (n,0) Carbon Nanotube Field Effect Transistors' I-V Characteristics: A Comparison of n=3a+1 and n=3a+2

Due to emergence of serious obstacles by scaling of the transistors dimensions, it has been obviously proved that silicon technology should be replaced by a new one having a high ability to overcome the barriers of scaling to nanometer regime. Among various candidates, carbon nanotube (CNT) field effect transistors are introduced as the most promising devices for substituting the silicon-based technologies. Since the channel of these transistors is made of CNT then its properties, such as chiral vector, have prominent effects on determining the performance of devices. In this paper the CNT diameter impact on tunneling and thermionic emission TE currents of a coaxially-gated CNTFET with doped source/drain extensions is investigated. The source/channel/drain of this transistor are a zigzag CNT with (n,0) chirality. The “n” value could be in the form of n = 3a + 1 or n = 3a + 2. By increasing the “a”, the diameter increases while the energy band gap EG of the CNT decreases; as a result by increasing the “a” value, the on/off current ratio decreases. However, for n = 3a + 2 the EG of a CNT shows a higher value; then at a given “a”, for n = 3a + 1 the on/off current ratio may decrease due to a lower EG and hence higher tunneling and TE current. Generally, subthreshold swing improves and threshold voltage increases for a lower diameter device; consequently, the leakage current could diminish. ON-state current and output conductance have higher values for a higher diameter. Also, the difference between EG and hence the I-V characteristics of the device with n = 3a +1 and n = 3a + 2 is negligible for a higher diameter value. All the results could be justified based on the energy-position resolved electron density and current spectrums on energy band diagram of the device.

Magnetic properties of MnF3 investigated by 55Mn NMR and M(H) measurement

The M(T) and M(H) curves were measured to study the spin-ordered state in MnF3 at low temperatures. In order to obtain the temperature dependence of magnetization, Mn3+ NMR resonance frequency was measured as a function of temperature. The resulting curve fits well to the initial temperature dependence of the magnetization expected for antiferromagnets with magnetic anisotropy, T3/2exp(−EG/kBT), with an energy gap EG of about 30K. From the comparison of the M(H) curve and classical theory, the relation between the anisotropy energy, Ka, and the exchange coupling constant between the nearest neighbors, J1, was found to be Ka∼−1.8J1+9.8 in the absolute temperature unit.

Boron-doped CuInTe2 semiconductor-sensitized liquid-junction solar cells

Boron-doped copper indium telluride nanoparticles (B-doped CuInTe2 NPs) sensitizer – for liquid-junction solar cells was demonstrated to improve cell performance. The NPs were grown using the successive ionic layer adsorption and reaction (SILAR) technique, with sizes of 7–9nm and a body-centered tetragonal structure formed on the TiO2 electrode. The band gaps (Egs) of boron-doped CuInTe2 NPs decreased from 0.73 to 0.64eV with increasing SILAR cycles. In comparison, Eg=0.83eV was yielded for an undoped CuInTe2 sample. The photovoltaic performance shows that the boron-doped CuInTe2(3) coated-TiO2 electrode exhibited the highest efficiency, η=0.18%, with a short-circuit current density, Jsc=2.11mA/cm2, an open-circuit voltage, Voc=0.459V, a fill factor, FF=18.9%. For the undoped sample, η=0.02% was also yielded. This kind of material and a synthesis procedure can be further improved for a higher efficiency and more stability on a sensitizer.

The effect of heat treatment on the optical properties of thin films of polyazomethine with flexible-side chains

Thermal stability of a soluble derivative of a basic aromatic polyazomethine: poly(1,4-(2,5-bisoctyloxy-phenylene-methylenenitrilo)-1,4-phenylene-nitrilomethylene) BOO-PPI, in thin films, has been studied by “in situ” UV-Vis-NIR transmission measurements during the heat treatment. Optical investigations of the BOO-PPI films have been completed by the wide angle X-ray diffraction (WAXRD) and atomic force microscopy (AFM) studies. Absorption spectra of the BOO-PPI films did not change during the first annealing, like as for unsubstituted PPI films. Study of temperature dependences of the absorption edge parameters (the Urbach energy EU and energy gap EG) allowed us assessment of changes in structural order, conformation and conjugation of the BOO-PPI polymer chain during the successive heating and cooling runs. The value of EG (2.19eV) was constant, while EU changed linearly in the range 71–140meV, within the temperature range 25–250°C. This reversible and recurrent dependence of EU is connected with the structural changes of flexible bis-octyloxy side chains, while the conjugation in the main chain is preserved (constant EG). Attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy studies confirmed invariable conjugation: C═N stretching vibration band was unchanged during the heat treatment.

CdTe Solar Cells: Processing Limits and Defect Chemistry Effects on Open Circuit Voltage

ABSTRACTThe role of CdTe solar cell processing on the defect chemistry that limits open circuit voltage (VOC) is addressed in the thermochemical processing regimes commonly encountered in present-generation CdTe devices. The highest VOC is 0.91 V for a bulk CdTe crystal with ITO which is only marginally higher than VOC = 0.86 V obtained for polycrystalline CdTe films with CdS. Both fall ∼0.4 V short of the VOC expected for CdTe, having band gap EG = 1.5 eV. The present >16% efficient superstrate CdTe cell uses a process based on high-temperature, T > 500°C, CdTe growth on CdS, coupled with optimized methods for incorporating oxygen, sulfur, copper, and chloride species in the CdTe film. Pushing cell conversion efficiencies beyond 20% will require increasing VOC beyond 1V. However the present pathway of processing optimization will likely yield VOC and efficiency converging on 0.9 V and <20%, respectively.

Structural, electronic and thermodynamic properties of Al- and Si-doped α-, γ-, and β-MgH2: Density functional and hybrid density functional calculations

In this work, we present a detailed study of Al- and Si-doped α-, γ-, and β-MgH2 phases using the gradient corrected density functional GGA-PBE and the hybrid Hartree–Fock density functionals PBE0 and HSE06 within the framework of generalized Kohn–Sham density functional theory (DFT) using a plane-wave basis set. We investigate the structural, electronic, and thermodynamical properties of these compounds with regard to their hydrogen storage effectiveness. PBE0 and HSE06 predict cell parameters and bond lengths that are in good agreement with the GGA-PBE calculations and previously known experimental results. As expected smaller band gaps (Egs) are predicted by GGA-PBE for the pure magnesium hydride phases. PBE0 overcomes the deficiencies of DFT in treating these materials better than HSE06 and yields Egs that compare even better with previous GW calculations. Both the hybrid functionals increase the Egs of the Al-doped magnesium hydrides by much less magnitudes than of the Si-doped phases. This difference is interpreted in terms of charge density distributions. Best H2 adsorption energies (ΔHads) are computed by HSE06 while GGA-PBE significantly overestimates them. Si-doped α- and β-MgH2 exhibited the least negative ΔHads in close proximity to the H2 binding energy range of −0.21 to −0.41 eV ideal for practical H2 storage transportation applications.

The High Energy Region of the Absorption Edge of a-Si:H, a Theoretical Study—III

In this paper we try to give a reasonable account for the origin of the experimental optical energy gap Eo of a-Si:H deduced from the plot due to Cody ( vs. E). Using a realistic model density of states diagram for a-Si:H and the constant dipole matrix element assumption, and a reasonable definition of the real optical energy gap EG, a new theoretical equation for ε2(E) was derived. The plot of the square root of this function as a function of the photon energy E for appropriate fitting parameters gives a straight line fit in the energy region of significance extrapolating to the energy axis at a value similar to the experimental optical gap but about 0.1 eV lower than the theoretical optical gap EG proposed in our paper. We conclude that the experimental optical gap Eo does not necessarily coincide with any optical transition threshold in the density of states diagram of a-Si:H.

Development of glycyrrhetinic acid-modified stealth cationic liposomes for gene delivery

The glycyrrhetinic acid-modified stealth cationic liposomes (GA–PEG–CLs) loaded with pDNA (GA–PEG–CLPs) were developed and found to transfect human hepatocellular carcinoma cell line HepG2 with high efficiency. GA–PEG–CLs were comprised of DOTAP, cholesterol (Chol) and glycyrrhetinic acid–polyethyleneglycol–cholesterol conjugate (GA–PEG–Chol). Agarose gel electrophoresis revealed that 5% GA–PEG–CLs constituted by DOTAP/Chol/GA–PEG–Chol at molar ratio of 50:45:5 could completely entrap pDNA at a lower liposomes/pDNA weight ratios of 4:1 (N/P ratio: 1.14). Compared to ordinary cationic liposomes (CLs), steric cationic liposomes (PEG–CLs) and 1% GA–PEG–CLs made from DOTAP/Chol/MPEG2000-Chol/GA–PEG–Chol at molar ratio of 50:45:4:1, 5% GA–PEG–CLs were found to possess the highest transfection efficiency as gene vectors in serum-free or serum-containing medium in PKCα over-expressed HepG2 cells but no significance difference in human embryonic kidney cell line HEK 293. Additionally, 5% GA–PEG–CLs have the lowest cytotoxicity on human normal hepatocyte cell line L02. The competitive inhibition experiments mediated by GA were carried out in HepG2 cells, which demonstrated that GA–PEG–CLs could deliver selectively pDNA to hepatoma cells by the targeting moiety GA. In conclusion, GA–PEG–CLs containing 5% GA–PEG–Chol might be one of the most potential gene vectors as hepatoma targeting therapy.