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In the aim of finding the optimal solar cell structure which allows better efficiency, stability and reduced cost, a general study of a Methyl Ammonium lead Iodide CH3NH3PbI3 based perovskite solar cell is made. Three different electron transport material compounds ETMs; TiO2, ZnO and SnO2 are comparatively studied considering the same hole transport material HTM, Spiro-OMeTAD. The photovoltaic parameters, i.e. the open circuit voltage (Voc), the short circuit current (Jsc) and the power conversion efficiency (PCE) are performed considering the ETM layers thicknesses, and the defect densities in both interfaces ETM/Perovskite and Perovskite/HTM. It is found that solar cell with SnO2 present the highest PCE for almost all configurations. Finally, the optimized cell is simulated with different organic and inorganic HTMs such as PEDOT: PSS, Cul and CuSbS2.

Elements based on nitride family and more specifically, those of the GaN/InGaN family, present a great interest for renewable energy conversion systems as they offer huge potentialities in photovoltaic applications, as example for the realization of concentration solar cells. This interest is linked to the possibility to enlarge the part of the solar energetic spectrum that a solar cell is able to capture thanks to the possibilities of growing multilayers cells with various band-gap and thus, with various absorption bands. In this paper, the performance of InGaN/GaN multiple quantum well MQW solar cells with respect to the N-polar orientation. is investigated. In order to obtain the exact conversion efficiency, the temperature effect as well as the spontaneous and piezoelectric polarization effect are taking into consideration in model. The results reveal that the increase of temperature decreases significantly the MQW solar cell efficiency. Our results and discussion would be helpful in designing and fabricating high efficiency InGaN/GaN solar cell in experiment.

In this work, simulations were performed to optimize the parameters of a lead-free perovskite/silicon tandem solar cell for the improved efficiency and stability of commercial devices. The top sub-cell is based on a lead-free perovskite with a large bandgap of 1.8 eV, an electron transport layer of SnO2/PCBM, which is known for its anti-hysteresis effect, and a hole transport layer of NiO to improve stability, whereas the bottom sub-cell is based on n-type silicon to increase the efficiency of the whole cell. First, the two sub-cells were simulated under standalone conditions for calibration purposes. Then, the current matching condition was obtained by optimizing the thicknesses of the absorber layers of both sub-cells and the doping concentration of the back surface field (BSF) layer of the silicon sub-cell. As a result of this optimization phase, thicknesses of 380 nm and 20 µm for the top and bottom sub-cells, respectively, and a doping concentration of 1022 cm–3 were used in the configuration of the tandem cell, yielding a large open-circuit voltage of 1.76 V and a power conversion efficiency of 24.4% for the whole cell. Finally, the effect of the working temperature was evaluated, and the results reveal that the high performance of lead-free perovskite sub-cells is less affected by an increase in temperature compared to lead-based solar cells, such as those based on CH3NH3PbI3 perovskite.

International audience; Among all the material parameters of a semiconductor, the lifetime of the carriers is one of the most complex, as it is a function of the dominant recombination mechanism, the number of carriers, the structural parameters and the temperature. Nevertheless, the lifetime of the carriers is a very useful and fundamental parameter to be determined for the qualification of the semiconductor in order to allow the improvement of the manufacturing process and the optimization of the operation of the semiconductor device. Thus being strongly linked to many physical and electronic parameters, the lifetime of the carriers cannot be provided only with a theoretical average value and an experimental measured value must be obtained. In the case of semiconductor junctions, precise measurements of the open-circuit voltage decay, OCVD, make it possible to trace the lifetime of the carriers through the device. An automated method for OCVD measurements presented in this contribution overcomes the main limitations that arise in the standard method when used for the characterization of the lifetime of carriers as it achieves the "open circuit conditions" of the device under test and reduces inherent noise of the differential operation mode of the method.

the rapid development in the field of organo-metal halide perovskite solar cells (PSCs) has led to the report of power conversion efficiency of > 25%. However, their large-scale deployment and possible commercialization endeavor are currently limited due to the thermal instability, interfaces defects. In order to study the effect of those reasons on the perovskite solar cell performances, a numerical simulation of n-i-p perovskite solar cell structure is presented in this paper. The design and the performances of CH3NH3PbI3 perovskite based solar cell have been studied. In the first part, we analyze the effect of defect density on both interfaces front side and back side of the absorber. Then, we had varied the carrier diffusion length of the perovskite layer in order to study the effect of the absorber quality on the solar cell parameters.

International audience; We report piezo-phototronic effects on the electrical properties of a Schottky contact metal/ZnO(n) solar cell. The piezo-phototronic effect is a three way coupling effect of piezoelectric, semiconductor and photonic properties occurring in non-central symmetric semiconductor materials when an applied strain to a semiconductor generates a piezoelectric potential controlling the carrier generation, transport, separation and/or recombination at the junction. The purpose of the present study is to determinate the influence of piezoelectric polarization on the electrical characteristics of this solar cell. Results show that the stress causes an increase of the electric field in the region where the piezoelectric fields are located. The sign of the stress proves that if it is positive (extensive strain), the effective barrier height increases which reduces the flow of electrons and thereafter is considered as a limiting factor for photovoltaic conversion, However, if the stress is negative (compression strain), a significant improvement of photovoltaic efficiency is obtained. Using the piezoelectric effects created by an external stress, our study provides not only a theoretical understanding about the piezo-phototronic effects on the characteristics of a solar cell but also assists for the possible design improvement allowing to increase.

This paper presents a model of a photovoltaic (PV) cell based on InGaN instead of regular cells made up of silicon, while polarization effects are considered. The model is constructed under Matlab/Simulink environment upon the equivalent electrical circuit of the PV cell. The way components of the equivalent electrical circuit are connected leads to establishing mathematical equations, thus, describing the behavior of the PV cell under different environmental and physical conditions. Once the PV cell model is validated by means of experimental results, it has been extended to build a model of a PV module made up of numerous cells interconnected in diverse potential configurations depending on the expected outputs in terms of current/voltage. The model has shown promising and accurate results and would aid researchers in the field of power electronics to consider it as a truthful PV generator (PVG).

In photovoltaic solar cells, p-n junctions have been considered a very promising structure to improve the carrier collection efficiency and accordingly the conversion efficiency. The basic processes for a solar cell to work are the generation of electron–hole pairs, separation, and recombination of those carriers in external circuits. The step of critical importance here is the electron–hole pair separation. The inner piezopotential, formed in the crystal by applying a stress which is called piezophototronic effect, interferes directly in the separation and recombination process, and consequently affects the solar cell performance. Recently, elaborated models including the piezophototronic effect were proposed to simulate metal/semiconductor and a p-n junction based in ZnO, but discussion of results has been limited to the output and the open-circuit voltage. In the present work, we will attempt to extend systematically the modeling of photovoltaic conversion on solar cell. The piezophototronic effect is included both in transport equation and photocurrent. Finally, the experimental results of organic solar cells support our theoretical model. Using the piezoelectric effect created by external stress, our study not only provides the first basic theoretical understanding about the piezophototronic effect on the characteristics of an inorganic solar cell, but also assists the design for higher performance solar cells.

This paper studies the impact of the temperature on GaN/ InGaN solar cell devices grown with N-polar orientations in electronic and photovoltaic properties. The self-consistent model is used to determine the energy band conduction. Using this model, we have computed a set of photovoltaic parameters allowing the evaluation of photovoltaic performance. Calculations were made as a function of indium composition and the host lattice temperature. As far as the effect of polarization is concerned, this discovery allows the manufacturing of high efficiency solar cells based on nitrides.

We present in this paper a new model of a InGaN PV module made up of numerous cells interconnected in diverse potential configurations. The spontaneous and the piezoelectric polarizations effects have been included within the Matlab/Simulink model. Using our model, one can use it, and determine all the necessary parameters under any new conditions of irradiance and temperature and then, obtain the I(V) and P(V) characteristics. The model has shown promising and accurate results and would aid researchers in the field of power electronics to consider it as a truthful PV generator (PVG).

This paper studies the impact of III-Nitride polarization on p-GaN/n-InGaN devices grown with N-polar orientations in photovoltaic properties. A new model taking account of the spontaneous and piezoelectric polarizations in the photocurrent density is developed. The self-consistent model as well is used to determine the energy band conduction. Using these models, we have computed a set of photovoltaic parameters allowing the evaluation of photovoltaic performance. Calculations were made as a function of indium composition and the host lattice temperature. As far as the effect of polarization is concerned, this discovery allows the manufacturing of high efficiency solar cells based on nitrides.

We propose in this paper a new and simple numerical model of an n-GaN/p-InGaN solar cell under Matlab/Simulink environment. We present an electrical equivalent model of the p-n solar cell along with a mathematical equations which describe the electrical behavior of the cell. The main contribution of this study consists in that the model handles both of physical and environmental impacts in a clear and efficient way. The obtained results would be accommodating to design and to fabricate a high solar cell performance.

International audience; We propose a new and simple analytical model taking into account of the polarization charge effects in order to assess the performance of InGaN-based PIN solar cells. The main contribution of this study consists in the derivation of new expressions of both diffusion and generation recombination currents to take into account of the polarization charges. The validity of the model is assessed through a comparison to numerical calculations, using the one dimensional self-consistent Schrödinger-Poisson equations and previously published theoretical and experimental works. The model is shown to be in a good agreement with experimental data. As expected, it is shown that the spontaneous and piezoelectric polarizations have a beneficial effect when the InGaN layer is grown on the N-face GaN/InGaN solar cells.

International audience; The present work reports on a theoretical study of spontaneous and piezoelectric polarization effects on the photovoltaic characteristics of InGaN/GaN multiple quantum well solar cells. More especially, it will prove that the use of heterostructures with N-face as a surface polarity can further improve the photovoltaic conversion. A new model including piezoelectric polarization is developed. In this paper, a part of simulation is also paid to analyze the dependence of the photocurrent density, the open circuit voltage, the output power and the efficiency versus the In composition and the number of quantum well units. As has been found, a maximum of energy conversion is expected to achieve 19 percent for optimum alloy composition. An attempt to explain the photovoltaic behavior of the solar cells in correlation of obtained results will be attempted.