Improvement Of Open-circuit Voltage Research Articles

Optimizing Bilayer Electrolyte Thickness Ratios for High-Performing Low-Temperature Solid Oxide Fuel Cells

Abstract Bilayer electrolytes for low-temperature solid oxide fuel cells (LT-SOFCs) offer the potential for higher power density by lowering the ohmic area specific resistance (ASR) and increasing the open circuit voltage (OCV) of mixed ionic/electronic conducting (MIEC) type electrolyte (e.g., GDC). However, optimizing the bilayer electrolyte thickness ratio is essential to achieve high power densities at low-temperatures (650-500℃). Herein we provide a systematic study of GDC/YCSB bilayer thickness ratios on anode-supported LT-SOFCs. In all cases the bilayer maximum power density (MPD) is higher than single-layer GDC based cells with reduced ohmic ASR values. Specifically, a high MPD of ~1 W/cm2 at 650℃ was achieved on a GDC(20 μm)/YCSB(12 μm) bilayer electrolyte based SOFC, which is 62% higher than single-layer GDC based SOFC (0.64 W/cm2) operating on humidified H2 as fuel. Such enhancement is due to the 9.3% improvement in OCV and 36% reduction in ohmic ASR values with the addition of the YCSB layer. The reduction in ohmic ASR of the bilayer electrolyte SOFCs is due to an increase of GDC electrical conductivity caused by the lower pO2 at the YCSB/GDC interface which must be considered in optimizing the thickness ratio of the bilayer electrolyte for achieving higher power density LT-SOFCs.

Perovskite half tandem v-shaped grating nanostructure solar cells: Improvement by light trapping and carrier transfer towards efficiency enhancement

In this paper, the enhancement of the perovskite solar cells (PSCs) efficiency through the implementation of a half-tandem structure featuring two absorbent layers of MAPbI3 and MoTe2 with a V-shaped nanostructured grating was investigated. MoTe2 was utilized as the second lower absorbent with a smaller bandgap than the first and upper absorbent, MAPbI3, to cover the incident light absorption in the infrared wavelength range. Additionally, the structure was also optimized by introducing a nanostructured V-shaped grating to increase the light propagation path and improve the absorption in the active layers. Also, the critical role of the electron transfer layer (ETL) and hole transfer layer (HTL) in carrier transfer and prevention of charge leakage was examined for materials including TiO2, TiO2-Gr (5%) nanocomposite, and Al-doped ZnO (AZO) as ETLs, and Cu2FeSnS4 (CFTS) and reduced Graphene Oxide (rGO) as HTLs in four distinct cell configurations. In this study, the optical and electrical models were solved to determine the optimal solar cell structure and materials through a comparative analysis of structures. Our findings revealed substantial improvements in short-circuit current density (Jsc), open-circuit voltage (Voc), and power conversion efficiency (PCE), where they increased from 15.27 to 31.55 mA/cm2, 0.91 to 1.30 V, and 11.78 to 27.63%, respectively. This resulted in a 2.35 times efficiency enhancement for the nanostructured V-shaped half-tandem solar cell with MAPbI3 (250 nm) and MoTe2 (150 nm) as absorbent layers, AZO (40 nm) as ETL and rGo (40 nm) as HTL compared to the planar non-tandem solar cell with MAPbI3 (250 nm) as absorbent layer, TiO2 (40 nm) as ETL and CFTS (40 nm) as HTL.

High-Efficiency Ternary Polymer Solar Cells with a Gradient-Blended Structure Fabricated by Sequential Deposition.

Acquiring the ideal blend morphology of the active layer to optimize charge separation and collection is a constant goal of polymer solar cells (PSCs). In this paper, the ternary strategy and the sequential deposition process were combined to make sufficient use of the solar spectrum, optimize the energy-level structure, regulate the vertical phase separation morphology, and ultimately enhance the power conversion efficiency (PCE) and stability of the PSCs. Specifically, the donor and acceptor illustrated a gradient-blended distribution in the sequential deposition-processed films, thus resulting in facilitated carrier characteristics in the gradient-blended devices. Consequently, the PSCs based on D18-Cl/Y6:ZY-4Cl have achieved a device efficiency of over 18% with the synergetic improvement of open-circuit voltage (VOC), short-circuit current density (JSC), and fill factor (FF). Therefore, this work reveals a facile approach to fabricating PSCs with improved performance and stability.

A Universal Perovskite/C60 Interface Modification via Atomic Layer Deposited Aluminum Oxide for Perovskite Solar Cells and Perovskite-Silicon Tandems.

The primary performance limitation in inverted perovskite-based solar cells is the interface between the fullerene-based electron transport layers and the perovskite. Atomic layer deposited thin aluminum oxide (AlOX ) interlayers that reduce nonradiative recombination at the perovskite/C60 interface are developed, resulting in >60 millivolts improvement in open-circuit voltage and 1% absolute improvement in power conversion efficiency. Surface-sensitive characterizations indicate the presence of a thin, conformally deposited AlOx layer, functioning as a passivating contact. These interlayers work universally using different lead-halide-based absorbers with different compositions where the 1.55 electron volts bandgap single junction devices reach >23% power conversion efficiency. A reduction of metallic Pb0 is found and the compact layer prevents in- and egress of volatile species, synergistically improving the stability. AlOX -modified wide-bandgap perovskite absorbers as a top cell in a monolithic perovskite-silicon tandem enable a certified power conversion efficiency of 29.9% and open-circuit voltages above 1.92 volts for 1.17 square centimeters device area.

Unveiling the role of vanadium doping in modulating morphological and electrical properties of piezoelectric Na0.46K0.46Li0.08NbO3 ceramics for energy harvesting

We report the enhancement of ferro/piezo-electric properties of lead-free alkali based perovskite Na0.46K0.46Li0.08NbO3 (NKLN) by vanadium doping (NKLNV) for high performing piezoelectric devices. Lead-free NKLN and NKLNV ceramics are synthesized via solid state reaction route as a substitute to the lead-based ceramic for the applications in sensors, transducers, and other electronic devices. The structural phase of synthesized ceramics is found to be pure perovskite as observed from powder X-ray diffraction. In dielectric studies, Curie temperature is found to be around 450 °C for both the samples. SEM images revealed the formation of homogeneous microstructure with well-defined grains. Dense polycrystalline ceramics having grain size of about 5 μm are obtained as a result of sintering at optimised temperature of 1050 °C. The micrographs showed that the grain size begins to evolve with reduced porosity in vanadium doped NKLN. Vicker's microhardness indentation test is performed for different loads at dwell time of 30 s, in which it was observed that the V-doping has enhanced the hardness. In ferroelectric studies, NKLNV shows higher value of remnant polarization as compared to NKLN as observed in P-E hysteresis loop. Fine microstructure and larger grain size felicitated the movement and reorientation of dipoles which resulted in enhanced piezoelectric coefficient for vanadium substituted NKLN ceramics. Flexible energy harvesters were fabricated by making a composite with PDMS, and then coating a thick film over ITO/PET sheet. NKLNV-based flexible device showed an improvement in open-circuit output voltage of 13.8 V under gentle finger tapping. NKLNV ceramics are a viable lead-free alternative for dielectric, piezoelectric, and ferroelectric applications.

Modifying Surface Termination by Bidentate Chelating Strategy Enables 13.77% Efficient Kesterite Solar Cells.

Surfaces display discontinuities in the kesterite-based polycrystalline films can produce large defect densities, including strained and dangling bonds. These physical defects tend to introduce electronic defects and surface states, which can greatly promote nonradiative recombination of electron-hole pairs and damage device performance. Here, an effective chelation strategy is reported to suppress these harmful physical defects related to unterminated Cu, Zn, and Sn sites by modifying the surface of Cu2 ZnSn(S,Se)4 (CZTSSe) films with sodium diethyldithiocarbamate (NaDDTC). The conjoint theoretical calculations and experimental results reveal that the NaDDTC molecules can be coordinate to surface metal sites of CZTSSe films via robust bidentate chelating interactions, effectively reducing surface undercoordinated defects and passivating the electron trap states. Consequently, the solar cell efficiency of the NaDDTC-treated device is increased to as high as 13.77% under 100mW cm-2 illumination, with significant improvement in fill factor and open-circuit voltage. This surface chelation strategy provides strong surface termination and defect passivation for further development and application of kesterite-based photovoltaics.

Modeling and Simulation of CZTS Solar Cell using Zn1-xMgxO as a buffer layer and Cul as a hole transport layer for efficiency improvement

This paper explores the impact of CZTS based solar cells using zinc magnesium oxide (Zn1-XMgXO) as a buffer layer and CuI (Copper iodide) as the hole transport layer using through SCAPS-1D(Solar Cell Capacitance Simulator) simulator. In the proposed work, the cell characteristics of the CZTS absorber layer, including electron affinity, defect density, and acceptor concentration, have been tuned. In addition, the study examines the effects of CBO which enhances the transfer of charge carriers by optimizing band alignment, Series resistance(Rs), Shunt resistance(Rsh), and Work Function (WF) of the metal contacts on the solar cell’s performance. From structures, CZTS/Zn1-XMgXO with x = 0.0652 demonstrated the highest PCE of 32.63% improvement in open circuit Voltage (Voc) = 1.0885 Volts, Short circuit density (Jsc) = 33.89, and fill factor (FF) = 88.43%.

Development of durable anion-exchange membranes using polyfluorene–based electrolytes and pore-filling method for direct formate fuel cells

Highly durable ether-linkage-free polyfluorene–based electrolytes with different ion exchange capacities (IECs) were synthesized, followed by the preparation and evaluation of cast and pore-filling (PF) membranes as anion exchange membranes (AEMs). The performance of these membranes was tested in direct formate fuel cells (DFFCs). The membrane properties, including formate permeability, were investigated to clarify the relationship between membrane performance and the performance of DFFCs. The formate permeability of the membrane was drastically affected by the existence of OH− anion, as OH− ions induce larger membrane swelling. In addition, the PF method was more effective in reducing the formate permeation than the cast membranes. The PF membrane using the polyelectrolyte with a low IEC value showed 20-fold lower formate permeability compared to that of the original cast membrane, leading to a higher improvement in open-circuit voltage (OCV), from 0.55 to 0.95 V in DFFCs. For the first time, a quantitative correlation between the formate permeability of AEMs and OCV values in DFFCs was established. From this correlation, formate permeation less than 0.03 mol L−1 h−1 is necessary to keep high OCV value. Using the developed membrane, we also demonstrated the high stability of DFFC at 80 °C for 5 days.

Multistep design simulation of heterojunction solar cell architecture based on SnS absorber

We report, a novel multi-step design simulation results on SnS absorber based solar cell architecture with is 4.5 times efficiency enhancement vis-à-vis reported experimental results. It is ascribed to an efficient control over inherent loss mechanism via device design novelty. The multi-step design modification in the device architecture comprised; (a) absorber bandgap widening at the interface, (b) considering donor interfacial defects at the SnS/buffer junction, (c) limiting the presence of the majority carrier at the interface via asymmetric doping at the SnS/buffer interfaces, and (d) employing back surface field at the absorber/back metal contact interface. This design approach resulted in achieving an optimal design configuration that exhibited significant improvements in open circuit voltage (119%), short circuit current (61%), fill factor (25.8%), and efficiency (347.6%) compared to the experimental benchmark. An overall effect of improved parameters, in the modified architecture of the SnS absorber based solar cell, led to substantial enhancement in efficiency close to ∼19% vis-à-vis 4.23% reported in literature.

Optimizing Bilayer Electrolyte Thickness Ratios for High Performing Low-Temperature Solid Oxide Fuel Cells

Over the last several years, significant developments have been made in bilayer electrolytes (e.g. GDC(Ce0.9Gd0.1O2-δ)/ESB((Er0.20Bi0.80O1.5)) suitable for low-temperature operating solid oxide fuel cells (SOFCs). Such bilayer electrolytes offer the potential for developing high performing LT-SOFCs by lowering the ohmic area specific resistance (ASR), and by improving the open circuit voltage (OCV) of mixed ionic/electronic conducting (MIEC) type electrolyte (e.g., GDC). However, optimizing the thickness ratio of the bilayer electrolyte is essential to achieve high power densities at low-temperatures (650-500 ℃). Here, we made a systematic study by varying the thickness ratios between GDC and YCSB((Bi0.75Y0.25)1.86Ce0.14O3±δ) bilayer electrolytes on an anode-supported LT-SOFCs, in all cases, the maximum power density (MPD) of the bilayer electrolyte cells is higher than pristine GDC based cells with reduced ohmic ASR values. Specifically, a high MPD of ~1 W/cm2 at 650 ℃ was achieved on a GDC(20μm) / YCSB(12μm) bilayer electrolyte based SOFC, which is 62% higher than pristine GDC based SOFC (0.64 W/cm2) operating on humidified H2 as fuel. Such enhancement is due to the 9.3% improvement in OCV (from 0.791 to 0.865 V) and a considerable 36% reduction in ohmic ASR values (from 0.094 to 0.069 Ω.cm2). Such reduction in ohmic ASR of the GDC/YCSB bilayer electrolyte SOFCs is due to the increase of GDC electrical conductivity as a result of lower pO2 at the interface of YCSB and GDC, and hence, must be considered in optimizing the thickness ratio of the bilayer electrolyte for achieving higher power density SOFCs. Figure 1

A DFT Study on the Impact of Saturated and Conjugated Side Chains on the Optoelectronic Performance of Y-series Nonfullerene Acceptors

Organic photovoltaic (OPV) consisting of nonfullerene acceptors have been found to be excellent candidates for harnessing solar energy. Extensive studies are being carried out to modify structures in a number of ways to enhance their efficiency. These include modifications in the acceptor part, use of efficient backbones and insertion of pi spacers. One strategy is the attachment of donor side chains for better assembly of molecules. In this work, the effect of theoretically designed side chains on electrochemical and optical properties of OPVs was studied. A series of molecules consisting of saturated (SC1-4) and conjugated donor (CD1-2) were designed and studied computationally for their potential OPV properties. Parameters like Band gap, absorption spectrum, frontier molecular orbital distribution, binding energy, fill factor, open circuit voltage, excitation energies, density of states (DOS) and transition density matrix (TDM) were studied using DFT and TD-DFT methods. Unsaturated side chains although exhibit better performance in terms of open circuit voltage and hole mobility but reduce light harvesting efficiency. All saturated side chain modifications showed improvement in fill factor and open circuit voltage than reference molecule. SC3 modification with red shift and smaller band gap showed the best performance.

Controlled conduction band offset in Sb2Se3 solar cell through introduction of (Zn,Sn)O buffer layer to improve photovoltaic performance: A simulation study

Enhancing the performance of antimony selenide (Sb2Se3) solar cells is significantly influenced by the optimization of the absorber/buffer junction. A wider bandgap buffer layer is suggested as a substitute for the traditional CdS buffer layer, for achieving this purpose. To enhance the short-circuit current density (Jsc) and mitigate parasitic absorption of Sb2Se3 cells, this study introduces zinc tin oxide (Zn,Sn)O as a substitute buffer layer instead of the narrow-bandgap and toxic CdS material. This study focuses on the simulation and numerical analysis of Sb2Se3 solar cells with (Zn,Sn)O buffer layer using the SCAPS (Solar Cell Capacitance Simulator) software. The photovoltaic performance was evaluated by investigating the impact of different fractions of x = Sn/(Zn + Sn) in the Zn1-xSnxO layer. The reduction of interface recombination and improvement of open-circuit voltage (Voc) can be attained by optimizing the band alignment through the Zn1-xSnxO layer. The most favorable interface between the Sb2Se3 and Zn1-xSnxO layers is attained when x = 0.2. In a traditional Sb2Se3/TiO2/CdS cell, the interface between the absorber and buffer layers has a −0.4 eV conduction band offset (CBO). The utilization of a Zn0.8Sn0.2O buffer layer causes an upward shift of the conduction band and a reduction of the negative CBO to −0.16 eV. Consequently, due to the wider gap between the conduction band of the Zn0.8Sn0.2O and the valence band of the Sb2Se3, interface recombination is reduced. According to the simulation results, the efficiency of the simulated Sb2Se3/TiO2/Zn0.8Sn0.2O cell is increased to 14.6%, representing a significant improvement compared to the conventional Sb2Se3/TiO2/CdS cell.

Molecular Bridge on Buried Interface for Efficient and Stable Perovskite Solar Cells.

The interface of perovskite solar cells (PSCs) is significantly important for charge transfer and device stability, while the buried interface with the impact on perovskite film growth has been paid less attention. Herein, we use a molecular modifier, glycocyamine (GDA) to build a molecular bridge on the buried interface of SnO2 /perovskite, resulting in superior interfacial contact. This is achieved through the strongly interaction between GDA and SnO2 , which also appreciably modulates the energy level. Moreover, GDA can regulate the perovskite crystal growth, yielding perovskite film with enlarged grain size and absence of pinholes, exhibiting substantially reduced defect density. Consequently, PSCs with GDA modification demonstrate significant improvement of open circuit voltage (close to 1.2 V) and fill factor, leading to an improved power conversion efficiency from 22.60 % to 24.70 %. Additionally, stabilities of GDA devices under maximum power point and 85 °C heat both perform better than the control devices.

Molecular Bridge on Buried Interface for Efficient and Stable Perovskite Solar Cells

AbstractThe interface of perovskite solar cells (PSCs) is significantly important for charge transfer and device stability, while the buried interface with the impact on perovskite film growth has been paid less attention. Herein, we use a molecular modifier, glycocyamine (GDA) to build a molecular bridge on the buried interface of SnO2/perovskite, resulting in superior interfacial contact. This is achieved through the strongly interaction between GDA and SnO2, which also appreciably modulates the energy level. Moreover, GDA can regulate the perovskite crystal growth, yielding perovskite film with enlarged grain size and absence of pinholes, exhibiting substantially reduced defect density. Consequently, PSCs with GDA modification demonstrate significant improvement of open circuit voltage (close to 1.2 V) and fill factor, leading to an improved power conversion efficiency from 22.60 % to 24.70 %. Additionally, stabilities of GDA devices under maximum power point and 85 °C heat both perform better than the control devices.

Realization of High-Efficiency Inverted Planar Perovskite Solar Cells Based on PEDOT: PSS Doped with Lithium Fluoride

The photovoltaic performance of perovskite solar cells with inverted structure depends on the conductivity of the hole transport layer and the charge transport rate to some extent. To further enhance the effect of the hole transport layer, lithium fluoride (LiF) was doped into poly (3,4-ethylene dioxythiophene)-polystyrene sulfonic acid (PEDOT: PSS) to improve its rate of conductivity and interfacial charge transport. The optimal photoelectric conversion efficiency of LiF-based perovskite solar cells that dope hole transport layer is 20.32% with negligible hysteresis, which is much higher than that of the control group (16.70%). Among all photovoltaic parameters, the improvement of open circuit voltage and fill factor is significant. LiF can not only promote the electrical characteristics of PEDOT: PSS and its hole mobility, but also optimize the quality of the upper perovskite film. Perovskite film shows a crystal orientation more conducive to hole transport on the modified hole transport layer, which obtains a dense and smooth absorption layer film. In this study, PEDOT: PSS-based perovskite solar cells with inverted structure doped with LiF are prepared, which provides a simple and effective method to commercialize perovskite solar cells.

End-cap modeling on the thienyl-substituted benzodithiophene trimer-based donor molecule for achieving higher photovoltaic performance

Despite the substantial advancements in organic solar cells (OSCs), the best devices still have quite low efficiencies due to less focus on donor molecules. With the intention to present efficient donor materials, seven small donor molecules (T1-T7) were devised from DRTB-T molecule by using end-capped modeling. Newly designed molecules exhibited remarkable improved optoelectronic properties such as less band gap (from 2.00 to 2.23 eV) than DRTB-T having band gap of 2.57 eV. Similarly, a significant improvement in λmax values was noticed in designed molecules in gaseous medium (666 nm–738 nm) and solvent medium (691 nm–776 nm) than DRTB-T having λmax values at 568 nm and 588 nm in gas and solvent phase respectively. Among all molecules, T1 and T3 exhibited significant improvement in optoelectronic properties such as narrow band gap, lower excitation energy, higher λmax values and lower electron reorganization energy as compared to pre-existed DRTB-T molecule. The better functional ability of T1-T7 is also suggested by an improvement in open circuit voltage (Voc) of designed structures (1.62 eV–1.77 eV) as compared to R (1.49 eV) when PC61BM is used as an acceptor. So, all our newly derived donors can be employed in the active layer of organic solar cells to manufacture efficient OSCs.

How Do Surface Polar Molecules Contribute to High Open-Circuit Voltage in Perovskite Solar Cells?

To date, the improvement of open-circuit voltage (VOC ) offers a breakthrough for the performance of perovskite solar cells (PSCs) toward their theoretical limit. Surface modification through organic ammonium halide salts (e.g., phenethylammonium ions PEA+ and phenmethylammonium ions PMA+ ) is one of the most straightforward strategies to suppress defect density, thereby leading to improved VOC . However, the mechanism underlying the high voltage remains unclear. Here, polar molecular PMA+ is applied at the interface between perovskite and hole transporting layer and a remarkably high VOC of 1.175V is obtained which corresponds to an increase of over 100mV in comparison to the control device. It is revealed that the equivalent passivation effect of surface dipole effectively improves the splitting of the hole quasi-Fermi level. Ultimately the combined effect of defect suppression and surface dipole equivalent passivation effect leads to an overall increase in significantly enhanced VOC . The resulted PSCs device reaches an efficiency of up to 24.10%. Contributions are identified here by the surface polar molecules to the high VOC in PSCs. A fundamental mechanism is suggested by use of polar molecules which enables further high voltage, leading ways to highly efficient perovskite-based solar cells.

Compact TiO2 layer by UV-assisted TiBr4 chemical bath deposition for perovskite solar cells

A new method to prepare a compact TiO2 layer for perovskite solar cells is introduced. The method features a UV-assisted chemical bath in an aqueous TiBr4 solution. The process does not require sophisticated systems to implement making scaling-up easy and the precursor ensures a uniform TiO2 layer with densely-packed planar grains. UV light provides an alternative to the temperature-assisted CBD process and eliminates the necessity to stir the solution during a deposition that opens new horizons for further scaling up PSCs. The new compact layer was compared to the spin-coated TiO2 layer and it was found that the novel method allows obtaining a more uniform layer with conformal coverage of the substrate. The new TiO2 layer was tested for perovskite solar cells and showed an improvement in open-circuit voltage (VOC) which can be explained by improved morphology and surface coverage of the TiO2 layer.

Nano Flex Screen Protectors for 2D Material Piezotronics

We propose nano flex film, a commercially available mobile screen protector, as a prospective flexible substrate for piezotronic devices. Reliable fabrication methods on flexible substrates and robust testing methods are essential to explore piezotronic properties in emerging 2D materials. Unlike conventional rigid substrates, flexible substrates are challenging to handle during fabrication and subsequent testing. The fabrication process on the proposed flexible substrate is as seamless as on rigid substrates. The optimized methods to fabricate 2D material devices on nano flex films are presented. Inorganic dielectric materials such as silicon dioxide (SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) offer good adhesion, better lifetime, and optical contrast to the 2D material flakes compared to polymer alternatives. The devices made on nano flex films with SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> have shown almost three-fold improvement in open circuit voltage generated (50 mV) and strain gauge values (1997 at 0.44% strain). Also, a simple setup proposed for strain-dependent electrical measurements enables us to characterize the piezotronic properties of different 2D materials without wire bonding or probe needles.

Atomic layer deposition of AlGaN alloy and its application in quantum dot sensitized solar cells

The role of plasma-enhanced atomic layer deposition growth of AlGaN ternary alloys on &lt;i&gt;c&lt;/i&gt;-planar sapphire substrates and the preparation of quantum dot-sensitized solar cells are explored in this work. The interface between the film and the substrate as well as the band gap of AlGaN ternary alloys during atomic layer deposition is dependent on Al component. At high Al fraction, there appears a good interface between the AlGaN alloy film and the substrate, however, the interface becomes rough when the Al fraction is reduced. The AlGaN alloy prepared by atomic layer deposition has a high band gap, which is related to the oxygen content within the film. Subsequently, CdSe/AlGaN/ZnS and CdSe/ZnS/AlGaN structured cells are prepared and analyzed for quantum dot solar cells from AlGaN films with an AlN/GaN cycle ratio of 1∶1. It is found that AlGaN can modify and passivate quantum dots and TiO&lt;sub&gt;2&lt;/sub&gt;, which can wrap and protect the structure of TiO&lt;sub&gt;2&lt;/sub&gt; and CdSe quantum dot, thus avoiding the recombination of photo-generated carriers. This modification effect is also reflected in the improvement of open-circuit voltage, short-circuit current, filling factor and photovoltaic conversion efficiency of quantum dot solar cells. These factors are discussed in this work, trying to modify carrier transport characteristics of AlGaN films prepared by atomic layer deposition.