Spectral Response Of Solar Cells Research Articles

Theoretical Study of Quantum Efficiency and Spectral Response of Solar Cells

A theoretical study of Quantum Efficiency (QE) and Spectral Response (SR) of solar cells was done in order to suggest ways in which related parameters could be optimized for maximum conversion efficiency of solar cells. Secondary data for the base, emitter and total parameters of QE and SR were obtained. MATLAB was employed in plotting and analysing these data across different diffusion lengths. From the results obtained, it was observed that when the value of the Emitter Diffusion Length (EDL) was varied from 0.3μm to 0.5μm, the emitter and total values of QE increased by about 700% at wavelength 300nm – 400nm. In the case of SR, it was observed that when there was an increase in the Base Diffusion Length (BDL) from 20μm to 50μm, there was an increase of about 26% at wavelength 800nm – 900nm. A rise in the diffusion length was seen to increase both the QE and SR of the cell. Thus, it can be suggested that an increase in the emitter and base diffusion length of a solar cell leads to a decrease in the recombination charges in the cell, giving more time for the charge carriers to exit the cell.

Fluorescent Waveguide Lattices for Enhanced Light Harvesting and Solar Cell Performance.

We present the properties and performance of fluorescent waveguide lattices as coatings for solar cells, designed to address the significant mismatch between the solar cell's spectral response range and the solar spectrum. Using arrays of microscale visible light optical beams transmitted through photoreactive polymer resins comprising acrylate and silicone monomers and fluorescein o,o'-dimethacrylate comonomer, we photopolymerize well-structured films with single and multiple waveguide lattices. The materials exhibited bright green-yellow fluorescence emission through down-conversion of blue-UV excitation and light redirection from the dye emission and waveguide lattice structure. This enables the films to collect a broader spectrum of light, spanning UV-vis-NIR over an exceptionally wide angular range of ±70°. When employed as encapsulant coatings on commercial silicon solar cells, the polymer waveguide lattices exhibited significant enhancements in solar cell current density. Below 400 nm, the primary mode of enhancement is through down-conversion and light redirection from the dye emission and collection by the waveguides. Above 400 nm, the primary modes of enhancement were a combination of down-conversion, wide-angle light collection, and light redirection from the dye emission and collection by the waveguides. Waveguide lattices with higher dye concentrations produced more well-defined structures better suited for current generation in encapsulated solar cells. Under standard AM 1.5 G irradiation, we observed nominal average current density increases of 0.7 and 1.87 mA/cm2 for single waveguide lattices and two intersecting lattices, respectively, across the full ±70° range and reveal optimal dye concentrations and suitable lattice structures for solar cell performance. Our findings demonstrate the significant potential of incorporating down-converting fluorescent dyes in polymer waveguide lattices for improving the current spectral and angular response of solar cell technologies toward increasing clean energy in the energy grid.

Solution-Processed SnO2 Quantum Dots for the Electron Transport Layer of Flexible and Printed Perovskite Solar Cells.

Flexible and printed perovskite solar cells (PSCs) fabricated on lightweight plastic substrates have many excellent potential applications in emerging new technologies including wearable and portable electronics, the internet of things, smart buildings, etc. To fabricate flexible and printed PSCs, all of the functional layers of devices should be processed at low temperatures. Tin oxide is one of the best metal oxide materials to employ as the electron transport layer (ETL) in PSCs. Herein, the synthesis and application of SnO2 quantum dots (QDs) to prepare the ETL of flexible and printed PSCs are demonstrated. SnO2 QDs are synthesized via a solvothermal method and processed to obtain aqueous and printable ETL ink solutions with different QD concentrations. PSCs are fabricated using a slot-die coating method on flexible plastic substrates. The solar cell performance and spectral response of the obtained devices are characterized using a solar simulator and an external quantum efficiency measurement system. The ETLs prepared using 2 wt% SnO2 QD inks are found to produce devices with a high average power conversion efficiency (PCE) along with a 10% PCE for a champion device. The results obtained in this work provide the research community with a method to prepare fully solution-processed SnO2 QD-based inks that are suitable for the deposition of SnO2 ETLs for flexible and printed PSCs.

New facility for primary calibration of differential spectral responsivity of solar cells using LDLS-based monochromatic source

A newly established setup for primary calibration and characterization of solar cells at NMCC/SASO is presented. This differential spectral responsivity (DSR) measurement instrument uses laser-driven light source (LDLS)-based modulated (AC) source to measure the spectral responsivity of photovoltaic (PV) detectors and solar cells. The setup is intended for measuring the spectral responsivity in the wavelength range from 250 nm to 2000 nm, bias level up to 1.5 kW/m2, with which a measurement uncertainty of 1.06 % (k = 2, in the range of 300 nm to 900 nm) could be achieved. We present validation measurements as well as spectral responsivity and external quantum efficiency (EQE) measurements of reference solar cells to demonstrate the objective of the setup. We present a preliminary evaluation of the associated uncertainty components as well as an uncertainty budget for validation, optimization and standardization of our setup.

Multijunction solar cell spectral response determination at radiation damage study

This paper discusses multijunction solar cells with optically coupled p-n junctions under radiation exposure photosensitivity spectral response study. It is shown that if the measurement technique does not consider the luminescent coupling and does not track the optical coupling degradation, then instead of a decrease (which is a natural response of a photoconverter to radiation damage), an abnormal increase in the narrow-bandgap photoresponse (receiving luminescent radiation) subcell due to radiation damage can be observed. Accordingly, with an increase in the irradiation dose, an increase in the subcell photocurrent forming a “negative” degradation dependence of MJ SC being used in space applications is recorded.

Numerical simulation and performance analysis of InGaP, GaAs, Ge single junction and InGaP/GaAs/Ge triple junction solar cells

Recent trends in the field of solar cells show that Multi-junction III-V semiconductor solar cells are an attractive option because of their high efficiency and cost effectiveness. As the first step to develop an InGaP/GaAs/Ge triple junction solar cell, we first simulated three individual InGaP, GaAs and Ge single junction solar cells using Silvaco ATLAS Software and obtained the efficiency of 13.42%, 12.99%, 3.37% for each cell respectively. Further in order to increase the efficiency of solar cell, we numerically simulated the InGaP/GaAs/Ge triple Junction solar cell by stacking InGaP, GaAs and Ge single junction solar cells and achieved high efficiency of 29.78%. The current–voltage curve, power-voltage curves and solar cell performance parameters and spectral response of each single junction solar cell as well as performance parameters and spectral response of InGaP/GaAs/Ge triple Junction solar cell have been extracted and analysed in detail. The aim of the study is to contribute to the investigation for experimental research work on the improvement of efficiency of InGaP/GaAs/Ge triple junction solar cell, through the numerical simulation, Since systematic cost of experimental investigation of the solar cell is very high and also it requires large time therefore technology computer aided design (TCAD) based simulation and performance optimization of the solar cells is important.

Optoelectronic Performance Analysis of Low-Energy Proton Irradiation and Post-Thermal Annealing Effects on InGaAs Solar Cell

The electrical and spectral properties of 150 KeV proton-irradiated MBE-grown In0.53Ga0.47As single junction solar cell and its post-thermal annealing properties were investigated. Both simulation and experimental methods were applied to analyze the irradiation-induced displacement damage and degradation mechanism of cell performance. The results show that most protons would penetrate through the In0.53Ga0.47As emitter and stop in the base region, causing differing extents of electric and spectral degredation. When proton fluence were 1 x 10(12) and 5 x 10(12) p/cm(2), the remaining factor of I-sc, V-oc, P-max,P- and FF were degraded to 0.790, 0.767, 0.558, 0.921 and 0.697, 0.500, 0.285, 0.817, respectively. Severer degradation was found in short wave lengths compared to long wave lengths of the solar cell spectral response. After annealing treatments, the normalized I-sc, V-oc, P-max, and FF, significantly recovered from 0.697, 0.500, 0.285, and 0.817 to 0.782, 0.700, 0.499, and 0.912 (fluence: 5 x 10(12) p/cm(2)), and the irradiation-induced defects in the whole emission area and part of the base area were annihilated, so the observed recovery of the short wavelength of the solar cell was greater than the long wavelength. The performance analysis in this work provided valuable ways to improve the photoelectric efficiency of space solar cells.

Optimization of front SiNx/ITO stacks for high-efficiency two-side contacted c-Si solar cells with co-annealed front and rear passivating contacts

In this contribution, we present an electron selective passivating contact metallised with a low temperature process to target front side applications in crystalline silicon (c-Si) solar cells. In addition to an interfacial silicon oxide (SiOx) and an in-situ phosphorous doped micro-crystalline silicon (μc-Si(n)) layer, it comprises an ultra-thin indium tin oxide (ITO) layer of 15 nm for lateral conductivity and a hydrogen rich silicon nitride (SiNx:H) layer which serves as hydrogen (H) reservoir and as anti-reflection coating. We use one single thermal treatment for 30 min at 350 °C to sinter the screen-printed paste, to recover sputtering damage induced during ITO deposition, and to diffuse hydrogen from the SiNx:H layer towards the c-Si/SiOx interface where it passivates interfacial defects.Applied to symmetrically processed textured samples, we find implied open-circuit voltage (iVOC) > 728 mV for optimal ITO thickness of 15 nm and annealing temperatures of 350 °C. The developed stack was applied on the front textured side of co-annealed (800 °C) p-type c-Si solar cells in combination with a tunnel oxide hole selective passivating contact on the rear side. We demonstrate solar cells with fill factor (FF) up to 81.9% and an open-circuit voltage (VOC) up to 719 mV. With a short-circuit current density (JSC) of 38.6 mA/cm2, we obtain a final cell efficiency to 22.8%. We find that the annealing of the SiNx:H/ITO stack strongly increases the ITO free carrier density penalizing the solar cell spectral response at high wavelengths.

Toward quantum efficiency enhancement of kesterite nanostructured absorber: A prospective of carrier quantization effect

In this work, the carrier confinement mechanism through nanostructures is studied in a copper-zinc-tin-sulfide/Cu2ZnSnSe4-type kesterite material, resulting in a remarkable performance enhancement of solar cells. The effect of the quantized energy band, recombination rate, and escape mechanism on the spectral response of solar cells is explored in detail. The mathematical model for carrier dynamics and performance measuring parameters are analyzed and optimized. Moreover, the number of quantum wells is incorporated gradually up to 100 and the corresponding performances are explored. It is observed that with the increase in the number of wells, photogenerated current density enhances significantly up to a saturation point and then deteriorates. A remarkable efficiency of 24.8% and more than 80% of quantum efficiency are achieved from 50 numbers of quantum wells with 79.8% of fill factor.

Annealing Effects on GaAs/Ge Solar Cell after 150 keV Proton Irradiation

Radiation-induced defects are responsible for solar cell degradation. The effects of radiation and annealing on the defects of a GaAs/Ge solar cell are modeled and analyzed in this paper. The electrical performance and spectral response of solar cells irradiated with 150 keV proton are examined. Then, thermal annealing was carried out at 120°C. We found that the proportion of defect recovery after annealing decreases with increasing irradiation fluence. The minority carrier lifetime increases with decreasing defect concentration, which means that the electrical performance of the solar cell is improved. We calculated the defect concentration and minority carrier lifetime with numerical simulation and modeled an improved annealing kinetic equation with experimental results.

Measurement setup for differential spectral responsivity of solar cells

We have developed a setup for measuring differential spectral responsivities of unifacial and bifacial solar cells under bias light conditions. The setup uses 30 high-brightness LEDs for generating a quasi-monochromatic light source covering the wavelength range 290–1300 nm. Halogen lamps are used to generate bias-lighting conditions up to the irradiance level of 1000 W/m2. The setup has been fully characterized for spectral irradiances and spatial uniformities of all light sources. Validation measurements carried out using a reference cell of 2 × 2 cm2 area from Fraunhofer ISE demonstrated an agreement better than 2% over the wavelength range of 425–940 nm, with an expanded uncertainty of 2.6%. In the UV and IR regions, the discrepancies are higher but still within estimated uncertainties. The setup is also tested in measuring spectral responsivities of large 15 × 15 cm2 bifacial solar cells. The associated problems are discussed.

Determining the spectral responsivity of solar cells under standard test conditions

The spectral responsivity of solar cells is widely used for cell analysis or calibration purposes. According to the IEC60904-8:2014 standard, the reference method for the determination of is the complete differential spectral responsivity approach. For this approach, the differential spectral responsivity is measured as a function of wavelength and bias irradiance. To obtain the spectral responsivity related to standard test conditions the IEC60904-8:2014 standard recommends to integrate via bias current for each wavelength. We show that this integration is wrong. It lacks analytical derivation and provides faulty curves for non-linear solar cells. We prove analytically and by means of simulations that the correct way of calculation is either the integration of via the bias irradiance or the integration of via the bias current , with being the AMx-weighted (e.g. AM1.5G or AM1.5D) differential responsivity. A simulation of the differential spectral responsivity of a strongly non-linear solar cell demonstrates deviations of up to 30% for (the wrong) integration of via at some wavelengths, corresponding to a deviation in the short-circuit current of up to 3.0%.

Enhancing the energy transfer from Mn4+ to Yb3+ via a Nd3+ bridge role in Ca3La2W2O12:Mn4+,Nd3+,Yb3+ phosphors for spectral conversion of c-Si solar cells

In this work, a series of Mn4+, Nd3+ and Yb3+ singly and co-doped Ca3La2W2O12 (CLWO) phosphors were prepared using a high-temperature solid-state reaction approach. In CLWO:0.016Mn4+, the emission spectrum presents a band around 709 nm attributed to Mn4+2Eg→4A2g transition under 365 nm UV excitation, which partly overlaps the excitation spectrum of Nd3+ singly doped CLWO phosphors. This indicates that a non-radiative resonant energy transfer process from Mn4+ to Nd3+ ions would like to take place in Mn4+, Nd3+ co-doped CLWO phosphors. Although scarce spectral overlap between Mn4+ emission and Yb3+ excitation in respective singly CLWO samples is observed, the energy transfer from Mn4+ to Yb3+ ions can also be deduced based on the analyses of excitation spectra, emission spectra and decay times in Mn4+, Yb3+ co-doped CLWO materials, which is proposed to be a phonon-assisted energy transfer process since the energy difference between Mn4+ lowest excited state 2Eg and Yb3+ excited state 2F5/2 is quite large. Moreover, in Nd3+, Yb3+ co-doped CLWO, the energy transfer phenomenon from Nd3+ to Yb3+ ions can be also observed. Therefore, we introduce Nd3+ ions into Mn4+, Yb3+ co-doped CLWO phosphors to realize the Mn4+→Nd3+→Yb3+ successive energy transfer process. Based on this, the Yb3+ emission intensity is highly enhanced in Mn4+, Nd3+ and Yb3+ tri-doped CLWO relative to Mn4+, Yb3+ co-doped CLWO. As a result, with the assistance of two channels Mn4+→Nd3+→Yb3+ and Mn4+→Yb3+ energy transfer processes, the broadband UV/blue light from sunlight spectrum can be effectively converted into Yb3+ near infrared (NIR), matching with the excellent spectral response of solar cells, which is highly expected to improve the c-Si solar cells spectral conversion efficiency.

Ultrawide Spectral Response of CIGS Solar Cells Integrated with Luminescent Down-Shifting Quantum Dots.

Conventional Cu(In1-x,Gax)Se2 (CIGS) solar cells exhibit poor spectral response due to parasitic light absorption in the window and buffer layers at the short wavelength range between 300 and 520 nm. In this study, the CdSe/CdZnS core/shell quantum dots (QDs) acting as a luminescent down-shifting (LDS) layer were inserted between the MgF2 antireflection coating and the window layer of the CIGS solar cell to improve light harvesting in the short wavelength range. The LDS layer absorbs photons in the short wavelength range and re-emits photons in the 609 nm range, which are transmitted through the window and buffer layer and absorbed in the CIGS layer. The average external quantum efficiency in the parasitic light absorption region (300-520 nm) was enhanced by 51%. The resulting short circuit current density of 34.04 mA/cm2 and power conversion efficiency of 14.29% of the CIGS solar cell with the CdSe/CdZnS QDs were improved by 4.35 and 3.85%, respectively, compared with those of the conventional solar cells without QDs.

Study of energy transfer and spectral downshifting in Ce, RE (RE = Nd and Yb) co-doped lanthanum phosphate

The phosphors LaPO4 (Lanthanum phosphate) doped with Ce(III)/Ce3+ and co-doped with Ce3+-Nd3+ and Ce3+-Yb3+ were effectively synthesized by conventional solid state reaction method. The prepared samples were characterized by powder X-ray diffraction (XRD) and surface morphology was studied by scanning electronic microscope (SEM). The photoluminescence (PL) properties were studied by spectrophotometers in near infrared (NIR) and ultraviolet visible (UV–VIS) region. Additionally the luminescence time decay curves of samples were investigated to confirm energy transfer (ET) process. The Ce3+-Nd3+ ion co-doped LaPO4 phosphors can convert a photon of UV region (278nm) into photons of NIR region (1058nm). While Ce3+-Yb3+ ion doped LaPO4 phosphors convert photons of UV region (278nm) into photons of NIR region (979nm). The Ce3+ ion acts like sensitizer and Nd3+/Yb3+ ions act as activators. Both kinds of emissions are suitable for improving spectral response of solar cells.

偏光光谱特性对太阳电池光谱响应的影响

偏光光谱特性对太阳电池光谱响应的影响

NIR Emission and Eu2+Nd3+ Energy Transfer in KSrCl3:Eu2+, Nd3+ phosphor

Solar energy is the most promising energy resource for its advantages of being inexhaustible and pollution-free. The most commonly used, commercial photovoltaic solar cells are fabricated with crystalline silicon. However, mismatch between the incident solar spectrum and spectral response of solar cells is the main reason to limit the cell efficiency presently 29%. The efficiency can be improved up to 38.4% by modifying the solar spectrum using phosphors. Phosphors can convert the high energy part of the solar spectrum into low energy in the near-IR (NIR) region which can be efficiently absorbed by the solar cells, also the removal of UV component from the incident radiation is expected to improve the stability. In this paper we report synthesis and efficient Eu2+ Nd3+ energy transfer in KSrCl3:Eu2+, Nd3+ phosphor which can be suitable as a spectrum modifier for the solar cell.

Design of outstanding random-patterns surface for enhancement of light scattering in Perovskite solar cell

Glass texturing is an efficient method for changing the surface morphology to enhance the solar cell spectral response. In this study, we present a method for optimizing the light scattering (LS) properties of uneven surface with random-patterns for perovskite solar cell (PSC) applications. Glass substrates were textured with a random structure assisted wet etching process using diluted hydrofluoric acid solution at a constant concentration of etchants. Then, the light trapping (LT) properties of suitable films were controlled over a wide range by varying the etching time (1–5[Formula: see text]min.). The optical properties of the surface and the reflection efficiency of the rugged surface should be maximized in the visible region at 5[Formula: see text]min. As a result in terms of short-circuit current density (Jsc), a gain of 23.0[Formula: see text]mA/cm2 (more than 29.9%) and power conversion efficiency (PCE) of 12.3% (more than 31.7%) are achieved with the introduction of textured interface.

Effect of spectral response of solar cells on the module output when individual cells are shaded

Solar cell characterization is carried out by current-voltage (I-V) and spectral response measurements. These characteristics of the solar cell depend on solar cell design, fabrication, material properties, junction depth and optical coatings. Generally, during module manufacturing, solar cells of similar wattage are used and spectral response (SR) including external quantum efficiency (EQE) and internal quantum efficiency (IQE) characteristics are not given any attention. It is observed that similar wattage rating crystalline solar cells have slight variation in their spectral response behavior over the wavelength range (300–1100nm). In this paper, the effect of shading on the crystalline solar cells of the module having same power output and slight difference in spectral response are experimentally investigated. The maximum and minimum drop in short circuit current of the module is observed to be 84.2% and 34.6% when the solar cells of high and low spectral response are shaded. Minority carrier diffusion length and dead layer thickness parameters of solar cells are also calculated from the short and long wavelength region of the spectral response curve. It is found that the effect on module output is high in case of shading a cell having maximum diffusion length and minimum dead layer length. It is concluded that spectral response of a solar cell is an additional parameter that must be considered apart from cell I-V characteristics in module fabrication for superior and uniform performance in the field.

20.0% Efficiency Si Nano/Microstructures Based Solar Cells with Excellent Broadband Spectral Response

Spectral response of solar cells determines the output performance of the devices. In this work, a 20.0% efficient silicon (Si) nano/microstructures (N/M‐Strus) based solar cell with a standard solar wafer size of 156 × 156 mm2 (pseudo‐square) has been successfully fabricated, by employing the simultaneous stack SiO2/SiNx passivation for the front N/M‐Strus based n+‐emitter and the rear surface. The key to success lies in the excellent broadband spectral responses combining the improved short‐wavelength response of the stack SiO2/SiNx passivated Si N/M‐Strus based n+‐emitter with the extraordinary long‐wavelength response of the stack SiO2/SiNx passivated rear reflector. Benefiting from the broadband spectral response, the highest open‐circuit voltage (Voc) and short‐circuit current density (Jsc) reach up to 0.653 V and 39.0 mA cm−2, respectively. This high‐performance screen‐printed Si N/M‐Strus based solar cell has shown a very promising way to the commercial mass production of the Si based high‐efficient solar cells.