GaAs Based InAs/InGaAs Quantum Dots-in-a-Well Solar Cells and Their Concentration Applications

2009 ◽  
Vol 1211 ◽  
Author(s):  
Kai Yang ◽  
Mohamed A El-Emawy ◽  
Tingyi Gu ◽  
Andreas Stintz ◽  
Luke F Lester
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Quantum Dot ◽  
Quantum Wells ◽  
Carrier Transport ◽  
Spectral Response ◽  
Cell Structure ◽  
Short Circuit ◽  
Control Cell ◽  
Photon Absorption

AbstractQuantum dot (QD) solar cells have been actively investigated recently since they have been theoretically shown to have the potential to realize high conversion efficiencies. However, very little research has analyzed the effect the dots have on the transport or recombination effects in the device. In this paper, we report the I-V and spectral response characteristics of InAs/InGaAs “dots-in-a-well” (DWELL) solar cells and compared them with GaAs control cells. The QD cells show higher short circuit density (Jsc) and better long-wavelength efficiency compared to the control cell. By comparing the dark current behavior of the QD cells to the GaAs control cells, we have conservatively estimated the concentration level at which the QD solar cells would surpass GaAs control devices.The quantum dot solar cells are grown by molecular beam epitaxy using the DWELL technique and a standard pin structure. The control cell structure is similar to the QD one except that there are no InAs dots or surrounding InGaAs quantum wells. The light I-V characteristics were measured under AM1.5G at 100 mW/cm2 illumination. The control cell has a Voc of 0.89V and a Jsc of 9.1 mA/cm2. The InAs QD solar cell has a Voc of 0.68 V and a Jsc of 12.2 mA/cm2. The QD cell has about a 33% larger short circuit current density compared to the GaAs control cell, which is mainly due to the higher photon absorption rate related to the DWELL structure. The spectrum response data show that the GaAs control cell and the QD cell have similar external quantum efficiency (EQE) in the visible to near-IR range (400-870nm). Beyond the GaAs absorption edge (870nm), the QD solar cell shows extended response with much higher measured EQE up to ˜1200 nm. This is strong evidence of the contribution from the InAs QDs and InGaAs QWs, the latter being the primary contributor to the increased Jsc.We calculated the “local” ideality factor from measured dark IV data, and then substituted it into a single diode equation to get the “local” reverse saturation current. Whereas the GaAs control shows the typical monotonically decreasing ideality from 0.3 to 0.8V, a linearly increasing ideality is observed in the QD cell. Based on the measured dark currents, and neglecting series resistance, we extrapolated the IV curves to higher voltages and found that they intercept at ˜2×104 mA/cm2. Dividing the intercept point Jdark by the Jsc of the QD cell conservatively estimates the light concentration (˜1400×) above which the QD cell would have a higher Voc than the GaAs cell assuming additivity applies. This result is mainly attributed to the unique carrier transport properties that are introduced into the solar cell devices that utilize QDs.

Effects of Temperature on I-V Characteristics of InAs/GaAs Quantum-Dot Solar Cells

2015 ◽  
Vol 1103 ◽  
pp. 129-135 ◽  
Author(s):  
Saichon Sriphan ◽  
Suwit Kiravittaya ◽  
Supachok Thainoi ◽  
Somsak Panyakaew
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Quantum Dot ◽  
Series Resistance ◽  
Cell Structure ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Substantial Improvement ◽  
Open Circuit ◽  
Gaas Quantum Dot

The current-voltage (I-V) characteristics of quantum-dot (QD) solar cells under illumination at various temperatures are presented. Stacked of high-density self-assembled InAs/GaAs QDs were incorporated into the Schottky-barrier-type solar cell structure. The I-V characteristics reveal that both short-circuit current and open-circuit voltage of the QD solar cell reduce when the measurement temperature increases. This result is unexpected and inconsistent with a basic solar cell theory where the temperature is believed to cause the enhancement of the short-circuit current. By considering the solar-cell circuit model, we can explain the obtained I-V curves by a high series resistance of the cell structure. Theoretical exclusion of the series resistance shows a substantial improvement of solar cell fill factor and efficiency. This work therefore suggests that reduction of series resistance by properly doping of the epitaxial layers can improve these devices.

Quantum Dot Spectral Tuning of Multijunction III-V Solar Cells

2008 ◽  
Vol 1121 ◽  
Author(s):  
Christopher Bailey ◽  
Seth Hubbard ◽  
Stephen J Polly ◽  
David V Forbes ◽  
Ryne P. Raffaelle
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Quantum Dot ◽  
Spectral Response ◽  
Short Circuit ◽  
Strong Dependence ◽  
Open Circuit ◽  
Partial Recovery ◽  
Single Junction ◽  
Strain Compensation

AbstractImproving the production of photocurrent in the middle junction of a InGaP/Ga(In)As/Ge triple-junction solar cells (TJSC) can improve the overall conversion efficiency of cell. One possible method to improve the middle junction photocurrent is inserting a quantum dot (QD) superlattice (SL) into the stack. It has been predicted that QD-SL enhanced TJSCs have an efficiency ceiling of 47% under a one-sun AM0 illumination spectrum. Additionally, QD array enhanced GaAs cells have the added benefit of possible intermediate band effects, anisotropic absorption and enhanced radiation tolerance. Embedding InAs quantum dots (QDs) in a single junction GaAs solar cell can increase sub-GaAs bandgap photocurrent generation. This method has been shown to improve the short circuit current density (Jsc) of single junction cells under simulated 1 sun air mass zero (AM0) illumination. However, the increase in strain due to the InAs QD self-assembly may cause defects that reduce the minority carrier lifetime resulting in losses in the cell open circuit voltage (Voc) on the order of 300-500 mV. The introduction of strain compensation (SC) layers into the superlattice (SL) structure of a QD solar cell has previously been shown to improve the device performance, including the partial recovery of Voc. Strain compensation can be used effectively to balance the residual strain, impede dislocation formation, and improve the solar cell characteristics. The effect of GaP strain compensation on the solar cell electrical and material properties was investigated. High resolution X-ray diffraction (HRXRD) scans along the symmetric (004) Bragg peak show weak intensity and wide FWHM at the zero order SL peak (SL0) for non-SC samples. Optimum SC thickness was theoretically determined using a zero in plane stress method and experimentally verified using HRXRD. Optimal strain compensation was then used to increase the QD SL stacking from 5x to 10x and 20x. Use of SC resulted in shifting of the SL0 peak toward the substrate peak as well as reduced FWHM and improved SL peak definition. Kinematical diffraction modeling of the QD structures using numerical simulation indicated this peak shift resulted from reduced overall strain in the SL stack up to 5ML of SC. The material quality improvement in the SC QD solar cells was manifested in an improved spectral response and Jsc. The optoelectronic results for GaAs solar cells with QD SL’s demonstrate a strong dependence on GaP SC layer thickness. In addition, comparison of multi junction (MJ) solar cells which incorporate the SC QD SL’s demonstrate the utility of additional sub-GaAs bandgap current contribution as a tool for additional current-matching optimization in MJ solar cells.

scholarly journals Quantum Dot Sensitized Solar Cell: Photoanodes, Counter Electrodes, and Electrolytes

Molecules ◽  
2021 ◽  
Vol 26 (9) ◽  
pp. 2638
Author(s):  
Nguyen Thi Kim Chung ◽  
Phat Tan Nguyen ◽  
Ha Thanh Tung ◽  
Dang Huu Phuc
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Quantum Dot ◽  
Photon Absorption ◽  
Dye Molecules ◽  
Charge Generation ◽  
Counter Electrodes ◽  
Advantages And Disadvantages ◽  
Efficiency Performance ◽  
Sensitized Solar Cells

In this study, we provide the reader with an overview of quantum dot application in solar cells to replace dye molecules, where the quantum dots play a key role in photon absorption and excited charge generation in the device. The brief shows the types of quantum dot sensitized solar cells and presents the obtained results of them for each type of cell, and provides the advantages and disadvantages. Lastly, methods are proposed to improve the efficiency performance in the next researching.

Design and Numerical Simulation on the Optical and Electrical Behavior of a ZnO:Al Nanowire Array a-Si pin Solar Cell

2008 ◽  
Vol 1101 ◽  
Author(s):  
Chang-Wei Liu ◽  
Zingway Pei ◽  
Shu-Tong Chang ◽  
Ren-Yui Ho ◽  
Min-Wei Ho ◽  
...  
Keyword(s):  
Solar Cell ◽  
Carrier Transport ◽  
Fill Factor ◽  
Cell Structure ◽  
Short Circuit ◽  
Nanowire Array ◽  
Short Circuit Current ◽  
Open Circuit ◽  
Si Solar Cell ◽  
Sun Light

AbstractOne of the parameters that limit the efficiency of a thin film solar cell, especially the a-Si and the nc-Si solar cell is the cell thickness. Although thicker film can absorb most of the sun light, the optical generated carriers will recombination through the numerous gap states in the film that obtained lower short circuit current and fill factor. In the controversy, thinner film could not absorb enough sun light that also limit the short circuit current. In this works, we utilize nanowire structure to solve the conflict between the light absorption and the carrier transport. The designed structure has ZnO:Al nanowire array on the substrate. The p-i-n a-Si solar cell structure is grown along the surface of each ZnO: Al nanowire sequentially. Under sunlight illumination, the light is absorbed in the axis direction of the nanowire. However, the carrier transport is along the radial direction of the solar cell. Therefore, the long nanowire could absorb most of the solar light. In the mean time, the thickness of the solar cell still is thin enough for photo-generated carrier transport. The dependence of short circuit current, open circuit voltage and fill factor to the length, diameter and density of ZnO:Al nanowires were simulated.

Space Radiation Effects in Advanced Solar Cell Materials and Devices

2001 ◽  
Vol 692 ◽  
Author(s):  
R. J. Walters ◽  
G. P. Summers
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Radiation Effects ◽  
Deep Level ◽  
Spectral Response ◽  
Cell Structure ◽  
Electrical Performance ◽  
Internal Cell ◽  
Particle Irradiation ◽  
Transient Spectroscopy

AbstractAn investigation of the physical mechanisms governing the response of III-V based solar cells to particle irradiation is presented. The effect of particle irradiation on single and multijunction solar cells is studied through current vs. voltage, spectral response, and deep level transient spectroscopy measurements. The basic radiation response mechanisms are identified, and their effects on the solar cell electrical performance are described. In particular, a detailed analysis of multijunction InxGa1-xP/InyGa1-yAs/Ge devices is presented. The MJ cell response is found to be more strongly affected by the internal cell structure than by the In content.

scholarly journals Novel Photonic Crystal Based Polycrystalline CdTe/Silicon Solar Cells

2020 ◽  
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Photonic Crystal ◽  
Conversion Efficiency ◽  
Current Density ◽  
Cell Structure ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Short Circuit Current Density ◽  
Silicon Solar Cells

In this paper, a novel photonic crystal (PhC) polycrystalline CdTe/Silicon solar cells are theoretically explained that increase their short circuit current density and conversion efficiency. The proposed structure consist of a polycrystalline CdTe/Silicon solar cell that a photonic crystal is formed in the upper cell. The optical confinement is achieved by means of photonic crystal that can adjust the propagation and distribution of photons in solar cells. For validation of modeling, the electrical properties of the experimentally-fabricated based CdS/CdTe solar cell is modeled and compared that there is good agreement between the modeling results and experimental results from the litterature. The results of this study showed that the solar cell efficiency is increased by about 25% compared to the reference cell by using photonic crystal. The open circuit voltage, short circuit current density, fill factor and conversion efficiency of proposed solar cell structure are 1.01 V, 40.7 mA/cm2, 0.95 and 27% under global AM 1.5 conditions, respectively. Furthermore, the influence of carrier lifetime variation in the absorber layer of proposed solar cell on the electrical characteristics was theoretically considered and investigated.

scholarly journals Enhanced Efficiency of MAPbI3 Perovskite Solar Cells with FAPbX3 Perovskite Quantum Dots

Nanomaterials ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 121 ◽  
Author(s):  
Lung-Chien Chen ◽  
Ching-Ho Tien ◽  
Zong-Liang Tseng ◽  
Jun-Hao Ruan
Keyword(s):  
Quantum Dots ◽  
Solar Cells ◽  
Solar Cell ◽  
Cell Structure ◽  
Short Circuit ◽  
Perovskite Solar Cells ◽  
Hole Transport ◽  
Transport Layer ◽  
Electron Transport Layer ◽  
Perovskite Quantum Dots

We describe a method to enhance power conversion efficiency (PCE) of MAPbI3 perovskite solar cell by inserting a FAPbX3 perovskite quantum dots (QD-FAPbX3) layer. The MAPbI3 and QD-FAPbX3 layers were prepared using a simple, rapid spin-coating method in a nitrogen-filled glove box. The solar cell structure consists of ITO/PEDOT:PSS/MAPbI3/QD-FAPbX3/C60/Ag, where PEDOT:PSS, MAPbI3, QD-FAPbX3, and C60 were used as the hole transport layer, light-absorbing layer, absorption enhance layer, and electron transport layer, respectively. The MAPbI3/QD-FAPbX3 solar cells exhibit a PCE of 7.59%, an open circuit voltage (Voc) of 0.9 V, a short-circuit current density (Jsc) of 17.4 mA/cm2, and a fill factor (FF) of 48.6%, respectively.

InAs Quantum Dot Development for Enhanced InGaAs Space Solar Cells

2004 ◽  
Vol 851 ◽  
Author(s):  
R. P. Raffaelle ◽  
Samar Sinharoy ◽  
C. William King ◽  
S. G. Bailey
Keyword(s):  
Quantum Dots ◽  
Solar Cells ◽  
Quantum Dot ◽  
Triple Junction ◽  
Spectral Response ◽  
Short Circuit ◽  
Theoretical Estimate ◽  
Inas Quantum Dots ◽  
Bottom Cell ◽  
Inas Quantum Dot

ABSTRACTThe majority of high-efficiency space solar cells being produced today are based on multi-junction devices of lattice-matched III-V materials. An alternative which has been receiving an increasing amount of attention is the lattice mis-matched or metamorphic approach to multi-junction cell development. In the metamorphic triple junction cell under development by ERI and its partners, the InGaAs junction (bottom cell) of the three-cell stack is the current limiting entity, due to the current matching which must be maintained through the device. This limitation may be addressed through the incorporation of InAs quantum dot array into the depletion region of an InGaAs cell. The InAs quantum dots in the InGaAs cell will provide sub-gap absorption and thus improve its short circuit current. This cell could then be integrated into the three-cell stack to achieve a space solar cell whose efficiency exceeds current state-of-the-art standards. A theoretical estimate predicts that a InGaAlP(1.95eV)/InGaAsP(1.35 eV)/InGaAs(1.2 eV) triple junction cell incorporating quantum dots to improve the bottom cell current would have an efficiency exceeding 40%. In addition, theoretical estimates have demonstrated that the use of quantum dot structures may also hold other cell benefits such as improved temperature coefficients and better radiation tolerance, which are especially important for utilization in space. As a first step towards achieving that goal, we have initiated the development of InAs quantum dots on lattice-mismatched InGaAs (1.2 eV bandgap) grown epitaxially on GaAs by metallorganic vapor phase epitaxy (MOVPE). These quantum dots have been characterized via photoluminescence (PL) and atomic force microscopy (AFM). A correlation exists between the quantum dot size and resulting optical band structure and can be controlled via the synthesis parameters. Quantum dots were incorporated into prototype InGaAs devices. A comparison of the resulting photovoltaic efficiency under simulated 1 sun intensity and air mass zero (AM0) illumination and spectral response demonstrated that an improvement in the long-wavelength photoconversion efficiency was achieved through the incorporation of the InAs quantum dots.

Preparation of Narrow-gap a-Si:H Solar Cells by VHF-PECVD Technique

2010 ◽  
Vol 1245 ◽  
Author(s):  
Do Yun Kim ◽  
Ihsanul Afdi Yunaz ◽  
Shunsuke Kasashima ◽  
Shinsuke Miyajima ◽  
Makoto Konagai
Keyword(s):  
Thin Films ◽  
Solar Cells ◽  
Solar Cell ◽  
Spectral Response ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Short Circuit Current Density ◽  
Open Circuit ◽  
Hydrogen Flow ◽  
Long Wavelength

AbstractOptical, electrical and structural properties of silicon films depending on hydrogen flow rate (RH), substrate temperature (TS), and deposition pressure (PD) were investigated. By decreasing RH and increasing TS and PD, the optical band gap (Eopt) of silicon thin films drastically declined from 1.8 to 1.63 eV without a big deterioration in electrical properties. We employed all the investigated Si thin films for p-i-n structured solar cells as absorbers with i-layer thickness of 300 nm. From the measurement of solar cell performances, it was clearly observed that spectral response in long wavelength was enhanced as Eopt of absorber layers decreased. Using the solar cell whose Eopt of i-layer was 1.65 eV, the highest QE at long wavelength with the short circuit current density (Jsc) of 16.34 mA/cm2 was achieved, and open circuit voltage (Voc), fill factor (FF), and conversion efficiency (η) were 0.66 V, 0.57, and 6.13%, respectively.

scholarly journals Suppression of Edge Recombination in InAs/InGaAs DWELL Solar Cells

2009 ◽  
Vol 1210 ◽  
Author(s):  
Tingyi Gu ◽  
Mohamed A El-Emawy ◽  
Kai Yang ◽  
Andreas Atintz ◽  
Luke F Lester
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Quantum Wells ◽  
Current Density ◽  
Open Circuit Voltage ◽  
Control Cell ◽  
Lateral Diffusion ◽  
Open Circuit ◽  
Constant Current ◽  
Short Current Density

AbstractThe InAs/InGaAs DWELL solar cell grown by MBE is a standard pin diode structure with six layers of InAs QDs embedded in InGaAs quantum wells placed within a 200-nm intrinsic GaAs region. The GaAs control wafer consists of the same pin configuration but without the DWELL structure. The typical DWELL solar cell exhibits higher short current density while maintaining nearly the same open-circuit voltage for different scales, and the advantage of higher short current density is more obvious in the smaller cells. In contrast, the smaller size cells, which have a higher perimeter to area ratio, make edge recombination current dominant in the GaAs control cells, and thus their open circuit voltage and efficiency severely degrade. The open-circuit voltage and efficiency under AM1.5G of the GaAs control cell decrease from 0.914V and 8.85% to 0.834V and 7.41%, respectively, as the size shrinks from 5*5mm2 to 2*2mm2, compared to the increase from 0.665V and 7.04% to 0.675V and 8.17%, respectively, in the DWELL solar cells. The lower open-circuit voltage in the smaller GaAs control cells is caused by strong Shockley-Read-Hall (SRH) recombination on the perimeter, which leads to a shoulder in the semi-logarithmic dark IV curve. However, despite the fact that the DWELL and GaAs control cells were processed simultaneously, the shoulders on the dark IV curve disappear in all the DWELL cells over the whole processed wafer. As has been discussed in previous research on transport in QDs, it is believed that the DWELL cells inhibit lateral diffusion current and thus edge recombination by collection first in the InGaAs quantum well and then trapping in the embedded InAs dots. This conclusion is further supported by the almost constant current densities of the different area DWELL devices as a function of voltage.

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