InGaN Solar Cells Research Articles

Optimization of InGaN-based solar cells by numerical simulation: Enhanced efficiency and performance analysis

The development of efficient solar cells is limited by the inability of the materials to absorb light from the entire solar spectrum. InGaN solar cells have become promising, due to the broad bandgap coverage of the solar spectrum from 0.7 eV to 3.42 eV. The performance of InGaN devices is simulated using SCAPS-1D software. The impacts of layer thickness and defect density on the performance of p-n and p-p-n junction InGaN solar cells were investigated, including holistic optimization of power conversion efficiency and quantum efficiency. A notable observation was the improvement in conversion efficiency with rising indium content, peaking at 23.8 % for In0.6Ga0.4N. For p-p-n junction cells, a thicker p-layer plus an additional thin top p-layer with a larger bandgap proved advantageous. The n-layer defect density in p-n junction cells showed minimal effects on open-circuit voltage and fill factor but reduced short-circuit current and efficiency as it increased. Conversely, the p-layer defect density influenced performance only at high densities beyond 1016 cm−3, while for p-p-n junctions, the top p-layer’s defect density had minimal impact. The optimized designs for both p-n and p-p-n junction cells, incorporating graded bandgaps, achieved optimal conversion efficiencies of 33.89 % and 34.07 %, respectively. The p-p-n design showed an enlarged high-efficiency area for suitable indium concentrations, offering broader indium concentration tuning possibilities and better lattice constant tuning. Quantum efficiency evaluations show the differences of defect densities and thicknesses across specific wavelength intervals, reaffirming the potential for strategic cell design choices.

Leveraging InGaN solar cells for visible light communication reception

AbstractSolar cells are increasingly being utilised for both energy harvesting and reception in free‐space optical (FSO) communication networks. The authors focus on the implementation of a mid‐band p‐In0.01Ga0.99 N/p‐In0.5Ga0.5 N/n‐In0.5Ga0.5 N (PPN) solar cell, boasting an impressive 26.36% conversion efficiency (under 1.5AM conditions) as a receiver within an indoor FSO communication network. Employing a solar cell with dimensions of 1 mm in length and width, the FSO system underwent simulation using Optisystm software, while the solar cell's behaviour was simulated using SCAPS‐1D. The received power from the solar cell was then compared to that of four commercially available avalanche photodiode (APD) receivers. Exploring incident wavelengths spanning 400–700 nm within the visible spectrum, across transmission distances of 5, 10, 15, and 20 m, the study presented current‐voltage (IV) and power‐voltage curves. Notably, the InGaN solar cell exhibited superior electrical power output compared to all commercial APDs. In conclusion, the findings underscore that augmenting received power has the potential to enhance FSO network quality and support extended transmission distances.

Numerical simulation of highly photovoltaic efficiency of InGaN based solar cells with ZnO as window layer

InxGa1-xN, as one promising nitride semiconductor alloys for modern optoelectronic devices, has received extensive attention in recent years. However, due to its powerful modulation of energy band gap from UV to visible spectra (0.7-3.4 eV) and its interesting absorption coefficient can range from 103 to 105 cm-1 , depending on the material properties, it can be considered as a potential candidate for high efficiency solar cells. The actual efficiency reached is (30.38%) [1]. In order to enhance more the efficiency, we perform in this work, a device modeling and numerical simulation using SCAPS software. We optimize the photovoltaic characteristics of a solar cell based on InxGa1-xN. This cell is mainly composed of indium gallium nitride semiconductors for both buffer and active layer p-InxGa1-xN/i-InxGa1-xN and the window layer contains of n-ZnO. The optimization of the various optoelectronic parameters allows improving performance of the solar cell, in addition to absorbing as much solar radiation as possible. The main photovoltaic parameters of the analog device: open circuit voltage, short circuit current density, fill factor and conversion efficiency (η) were compared and analyzed. We have reached the conversion efficiency of 26.11% for a thickness of 1450 nm and an n-doping of 3×1018 cm-3 in the active layer (In0.3Ga0.7N). This study investigates the great potential of InGaN solar cells and can be used for the design and manufacture of high efficiency III-nitride based solar cells.

Design and fabrication process flow for high-efficiency and flexible InGaN solar cells

We present the design of high-efficiency and flexible InGaN solar cells based on nano-pyramid absorbers, which allows for high indium incorporation and reduced polarization effects while maintaining high crystalline quality. The process uses nanoscale selective area growth and van der Waals epitaxy on two-dimensional (2D) hexagonal boron nitride on sapphire substrates. The 2D layer enables mechanical release of solar cells via self-lift-off and its transfer to a flexible substrate. Through coupled optical and electrical simulations, we compare different designs of the p- and n-regions and propose two device architectures that combine mechanical flexibility and high power conversion efficiency (up to 16.4%). This approach can provide a solution for the fabrication of high-efficiency, low-cost and flexible InGaN-based solar cells.

Numerical Approach of Single-Junction InGaN Solar Cell Affected by Carrier Lifetime and Temperature

The PC1D simulation aand origin software were successfully used for the study of Carrier Lifetime and Temperature effect on InGaN Single-Junction Solar Cell. For the simulation, the total device area was 100 cm2, dielectric constant 13.1, band gap 1.35eV, intrinsic constant is 1×1010 cm-3, doping concentration is 1×1017 cm-3, electron number and hole number 1000 and 170 respectively, and the refractive index was 3.58. The optimized temperature and bulk recombination were 25°C and 1000μs respectively along with the efficiency of 18.258 % for both n and p - InGaN solar cell. Several graphs were plotted under the following conditions: a) bulk recombination time of p-InGaN and temperature are kept constant at 1000 μs and 25°C, the variation of bulk recombination time of n - type InGaN solar cell with base current and voltage, maximum current and voltage, and efficiency and maximum power were studied. b) bulk recombination time of n-InGaN and temperature are kept constant at 1000 μs and 25°C, the variation of bulk recombination time of p - type InGaN solar cell with base current and voltage, maximum current and voltage, and efficiency and maximum power were studied.

Modeling of temperature dependence of Λ-graded InGaN solar cells for both strained and relaxed features

The temperature dependence of Λ-graded InGaN solar cells is studied through simulation using nextnano software. Λ-Graded structures have been designed by increasing and then decreasing the indium composition in epitaxial InGaN layers. Due to polarization doping, layers of p-type and n-type doping arise without the need for impurity doping. Different individual structures are designed by varying the indium alloy profile from GaN to maximum indium concentrations, xmax, ranging from 20% to 90% pseudomorphically strained to a GaN substrate and from 20% to 100% for completely strain-relaxed materials and linearly decreases back to GaN. For InxGa1-xN with x>∼0.9, if the material is strained to the GaN lattice constant, it is predicted to have a negative band gap. So this case is not considered here. The temperature dependence of the electrical and optical properties as they relate to the solar efficiency of the Λ-graded structures under relaxed and strained conditions are studied. Additionally, the dimensionless absorption coefficients are fitted and plotted as functions of the band gap under both strained and relaxed conditions at different temperatures. As a result, the generation rates as functions of the penetration depth within a cell can be calculated in order to obtain the solar cell parameters including efficiency for each Λ-graded structure at different temperatures. Under the strained condition, the xmax, where the solar cell efficiency reaches its maximum for each temperature, decreases as the temperature increases. At the same time, under the relaxed condition, at low temperatures (T = 100–400 K), xmax is 100%, that is, grading to InN results in maximum efficiency, while at higher temperatures (T = 500–800 K), xmax decreases with the increasing temperature.

Influence of Doping Concentration and Thickness of Regions on the Performance of InGaN Single Junction-Based Solar Cells: A Simulation Approach

The impact of doping concentration and thickness of n-InGaN and p-InGaN regions on the power conversion efficiency of single junction-based InGaN solar cells was studied by the Silvaco ATLAS simulation software. The doping concentration 5 × 1019 cm−3 and 1 × 1015 cm−3 were optimized for n-InGaN and p-InGaN regions, respectively. The thickness of 300 nm was optimized for both n-InGaN and p-InGaN regions. The highest efficiency of 22.17% with Jsc = 37.68 mA/cm2, Voc = 0.729 V, and FF = 80.61% was achieved at optimized values of doping concentration and thickness of n-InGaN and p-InGaN regions of InGaN solar cells. The simulation study shows the relevance of the Silvaco ATLAS simulation tool, as well as the optimization of doping concentration and thickness of n- and p-InGaN regions for solar cells, which would make the development of high-performance InGaN solar cells low-cost and efficient.

COMSOL Simulation of Heat Distribution in InGaN Solar Cells: Coupled Optical-Electrical-Thermal 3-D Analysis

Thermal distribution in solar cells has been rarely investigated despite it significant impact on the performance. The current contribution presents a COMSOL Multiphysics 3-D analysis of the electrical and optical photogeneration properties in relation with the heat distribution in InGaN solar cell. For this simulation, we have coupled the “Semiconductor Module”, the “Heat Transfer Module for Solids,” and the “Wave Optics Module” allowing us to calculate the Shockley–Read–Hall heating, the total heat flux, the Joule heating the carrier’s concentration, the electric field, and the temperature dissipation in the InGaN solar cell structure. Despite the fact that the achievements of InGaN solar cells are still mostly at the state of laboratory studies, the current contribution presenting original results on coupled phenomena occurring in the cells makes it possible to highlight new possible guidelines for an improve of their efficiency.

Study of simulations of double graded InGaN solar cell structures

The performances of various configurations of InGaN solar cells are compared using nextnano semiconductor simulation software. Here, we compare a flat base-graded wall GaN/InGaN structure, with an InxGa1−xN well with sharp GaN contact layers, and an InxGa1−xN structure with InxGa1−xN contact layers, i.e., a homojunction. The doping in the graded structures is the result of polarization doping at each edge (10 nm from each side) due to the compositional grading, while the well structures and homojunctions are impurities doped at each edge (10 nm from each side) at levels equal to the polarization doping density in the graded structure with similar maximum indium concentration. The solar cells are characterized by their open-circuit voltage, Voc, short circuit current, Isc, solar efficiency, η, and energy band diagram. The results indicate that an increase in Isc and η results from increasing both the fixed and maximum indium compositions, while the Voc decreases. The maximum efficiency is obtained for the InGaN well with 60% In.

Polarization-induced hole doping for long-wavelength In-rich InGaN solar cells

The lack of high-quality In-rich p-type InGaN restricts the development of high-efficiency InGaN solar cells toward the whole solar spectrum. In this work, we report a polarization-induced (PI) hole doping method for In-rich InGaN by using the In composition graded p-type InGaN layer with lightly Mg doping. The hole mobility as high as ∼40 cm2/V s is obtained, which is more than ten time higher than that of the single-layer p-type InGaN with the same average In mole fraction. The In-rich InxGa1−xN (x ∼ 0.4) solar cell with the PI doped p-type InGaN exhibits a peak absorption at the wavelength as long as 594 nm. As a result, the conversion efficiency of InGaN solar cell is improved by over 1.5 times compared to that with single-layer p-type InGaN.

High conversion and quantum efficiency indium-rich p-InGaN/p-InGaN/n-InGaN solar cell

In this paper, an efficient three-layered p-In0.6Ga0.6N/p-In0.7Ga0.7N/n-In0.7Ga0.7N (PPN) solar cell was designed. The characteristics of the PPN-junction InGaN solar cell were simulated using the SCAPS-1D software. The effects of the thickness and carrier density of the PPN layer on solar cell performance were evaluated. The results were compared with those of the performance of the PN-junction solar cell. Results revealed that a thin top p-InGaN with a high carrier density had a considerable influence on the performance of the solar cell. Adding a p-InGaN layer as thin as 0.01 μm on the top of the PN-junction solar cell substantially improved the conversion efficiency of the solar cell from 21.39% (PN) to 30.23% (PPN).

InGaN/GaN multi‐quantum‐well solar cells under high solar concentration and elevated temperatures for hybrid solar thermal‐photovoltaic power plants

AbstractHybrid solar electricity generation combines the high efficiency of photovoltaics (PVs) with the dispatchability of solar thermal power plants. Recent thermodynamic analyses have shown that the most efficient strategy constitutes an integrated concentrating PV‐thermal absorber operating at high solar concentration and at the high temperatures suitable to efficient commercial steam turbines (~673–873 K). The recuperation of PV thermalization losses and the exploitation of sub‐bandgap photons can more than compensate for the inherent decrease of PV efficiency with temperature in properly tailored tandem solar cells for which promising candidates are III–N alloys. Recently, there have been considerable efforts to develop apposite InGaN solar cells by producing InGaN/GaN multiple quantum wells (MQWs) as the top cell in a tandem PV device that would absorb the short‐wavelength regime of the solar spectrum, while sub‐bandgap photons and PV thermalization are absorbed in the thermal receiver.We present measurements of current–voltage curves and external quantum efficiency spectra for InGaN/GaN MQW solar cells under high sunlight intensity, up to 1 W/mm2 (1000 suns) and elevated temperature, up to 723 K. We find that the short‐circuit current increases significantly with temperature, while the magnitude of the temperature coefficient of the open‐circuit voltage decreases with solar concentration according to basic photodiode theory. Conversion efficiency peaks at 623–723 K under ~300 suns, with no perceptible worsening in cell performance under extensive temperature and irradiance cycling—an encouraging finding in the quest for high‐temperature high‐irradiance cells.

Effect of light wavelengths on the non-polar InGaN-based thin film solar cells performances using one-dimensional modeling

Abstract In the present contribution, we determine the effect of light wavelength variation on the performances of the non-polar InGaN-based solar cells in order to find the optimum light wavelength that yields a high efficiency. The calculations are performed using a one-dimensional SCAPS-1D tool (One-Dimensional Solar Cell Capacitance Simulator). The simulation has been carried out by lighting through a n-In0.3Ga0.7As layer. An efficiency of 12.24% with the fill-factor FF = 51.35%, open-circuit voltage VOC = 0.72 V and short-circuit current density JSC = 32.80 mA/cm2 is obtained under AM1.5G illumination. The quantum efficiency characteristic displays a maximum value of more than 90% in the visible range using AM1.5G illumination. Moreover, our results show that with increasing light wavelengths from the blue light (around 450 nm) to the end of the red light (around 700 nm), the efficiency increases from 13.76% to above of 20%. The short-circuit current density is also increased from 37.33 mA/cm2 to 53.81 mA/cm2 with increasing light wavelengths from 450 nm to 700 nm. However, the variation of the light wavelength seems to have only a small influence on the open-circuit voltage and fill-factor. The present study provides information about the properties of the materials used in the cell structure of efficient InGaN solar cells.

Numerical Simulation of Single Junction InGaN Solar Cell by SCAPS

The performance of the InGaN single-junction thin film solar cells has been analyzed numerically employing the Solar Cell Capacitance Simulator (SCAPS-1D). The electrical properties and the photovoltaic performance of the InGaN solar cells were studied by changing the doping concentrations and the bandgap energy along with each layer, i.e. n-and p-InGaN layers. The results reveal an optimum efficiency of the InGaN solar cell of ~ 15.32 % at a band gap value of 1.32 eV. It has been observed that lowering the doping concentration NA leads to an improvement of the short circuit current density (Jsc) (34 mA/cm2 at NA of 1016 cm−3). This might be attributed to the increase of the carrier mobility and hence an enhancement in the minority carrier diffusion length leading to a better collection efficiency. Additionally, the results show that increasing the front layer thickness of the InGaN leads to an increase in the Jsc and to the conversion efficiency (η). This has been referred to the increase in the photogenerated current, as well as to the less surface recombination rate.

Nanopyramid-based absorber to boost the efficiency of InGaN solar cells

InGaN nano-structures, grown using nano selective area growth, have been shown to exhibit high crystalline quality, even for high In content InGaN alloy, and reduced polarization charge effect. They are thus very attractive for the realization of high efficiency solar cells. Compared to planar InGaN absorbers, nanopyramid-based absorbers are shown to relax the usual challenging constraint on the doping of the p-GaN layer, which would be needed to overcome the polarization-induced electric field. NP-based solar cells maintain the same performance with ten times lower p-GaN doping. Furthermore, the SiO2 mask used for selective area growth of the nanopyramids is shown to help trap light into the nanopyramids, leading to increased optical absorption and thus efficiency. Last, InGaN nanopyramid absorber-based solar cells can allow for a higher InGaN residual donor concentration than that of the planar InGaN solar cells. Overall, an optimized In0.3Ga0.7N nanopyramid-based solar cell can lead to an efficiency twice than that of a planar InGaN-based solar cells with standard p- and n-GaN doping level. As a proof of concept, an In0.09Ga0.91N nanopyramid-based solar cell has been fabricated and is shown to have larger short circuit photocurrent and open circuit voltage than a state of the art In0.08Ga0.92N-based planar solar cell.

Novel semiconductors for sustainable solar energy technologies

Novel materials must be found in order to develop advanced sustainable solar energy technologies. This paper presents recent research being pursued by my group at Arizona State University in the study and development of III-V semiconductors for improving the efficiency of photovoltaic devices beyond the Shockley-Queisser limit. Although in the early stages of development, significant advances are happening in two directions described here. One is for intermediate-band solar cells, using InAs quantum dots in wide gap III-V semiconductor thin films. The other is for double-junction InGaN solar cells for high-temperature applications. The theoretical efficiencies of these two system resemble that of triple-junction cells, at above 60%.

Efficiency Improvement Approach of InGaN Based Solar Cell by Investigating Different Optical and Electrical Properties

The basic destinations of setup of solar cell is touplift it`s capability. IndiumGalliumNitride is a composition that has encountered expansive research since 2002 as a potential photovoltaic material. Fluctuations in the arrangement of InN and GaN inside InGaN, the band gap of this semiconductor material can be changed. Subsequently, a high-effectiveness solar cell can be conceivably created by having a few InGaN intersections.The utilization of Silvaco Atlas as a reenactment apparatus can help in recognizing whether InGaNcan be utilized for photovoltaics. The paper examines the effect of the temperature on InGaN solar cell gadgets developed with N-polar introductions in electronic and photovoltaic properties. The self-reliable model is utilized to decide the vitality band conduction. Indium gallium nitride and other PV materials offer the open door for restricted bandgap designing to coordinate spectra. The impacts of barometrical conditions, for example, mist concentrates, overcast cover, water vapor, and air mass have been appeared to cause varieties in spectral brilliance that changes PV framework execution because of both misrepresenting and underestimating. Structuring PV gadgets streamlined for unearthly brilliance of a specific area can result in enhanced PV framework execution. The consequences of this strategy are outlined for the contextual investigation of solar ranches in the Indian areas and circle utilized.

InGaN solar cells with regrown GaN homojunction tunnel contacts

Highly doped GaN p–n tunnel junction (TJ) contacts to InGaN solar cells are demonstrated, in which the TJs were grown by molecular beam epitaxy on top of active solar cell regions grown by metalorganic chemical vapor deposition. The effects of Si and Mg doping concentrations on solar cell characteristics are studied and used to improve turn-on voltage and series resistance. The highest doped cell with a TJ has an open-circuit voltage of 2.2 V, similar to that of the control cell fabricated using indium tin oxide (ITO), and a far less short-circuit current density loss from unwanted photogeneration in the TJ contact than in the ITO contact.

Energy band engineering of InGaN/GaN multi-quantum-well solar cells via AlGaN electron- and hole-blocking layers

In this paper, we perform a comprehensive study on energy band engineering of InGaN multi-quantum-well (MQW) solar cells using AlGaN electron- and hole-blocking layers. InGaN MQW solar cells with AlGaN layers were grown by metalorganic chemical vapor deposition, and high crystal quality was confirmed by high resolution X-ray diffraction measurements. Time-resolved photoluminescence results showed that the carrier lifetime on the solar cells with AlGaN layers increased by more than 40% compared to that on the reference samples, indicating greatly improved carrier collections. The illuminated current-density (J–V) measurements further confirmed that the short-circuit current density (Jsc) of the solar cells also benefited from the AlGaN layer design and increased 46%. At room temperature, the InGaN solar cells with AlGaN layers showed much higher power conversion efficiency (PCE), by up to two-fold, compared to reference devices. At high temperatures, these solar cells with AlGaN layers also delivered superior photovoltaic (PV) performance such as PCE, Jsc, and fill factor than the reference devices. These results indicate that band engineering with AlGaN layers in the InGaN MQW solar cell structures can effectively enhance the carrier collection process and is a promising design for high efficiency InGaN solar cells for both room temperature and high temperature PV applications.

Reliability analysis of InGaN/GaN multi-quantum-well solar cells under thermal stress

We investigate the thermal stability of InGaN solar cells under thermal stress at elevated temperatures from 400 °C to 500 °C. High Resolution X-Ray Diffraction analysis reveals that material quality of InGaN/GaN did not degrade after thermal stress. The external quantum efficiency characteristics of solar cells were well-maintained at all temperatures, which demonstrates the thermal robustness of InGaN materials. Analysis of current density–voltage (J–V) curves shows that the degradation of conversion efficiency of solar cells is mainly caused by the decrease in open-circuit voltage (Voc), while short-circuit current (Jsc) and fill factor remain almost constant. The decrease in Voc after thermal stress is attributed to the compromised metal contacts. Transmission line method results further confirmed that p-type contacts became Schottky-like after thermal stress. The Arrhenius model was employed to estimate the failure lifetime of InGaN solar cells at different temperatures. These results suggest that while InGaN solar cells have high thermal stability, the degradation in the metal contact could be the major limiting factor for these devices under high temperature operation.