Multijunction solar cell model for translating I–V characteristics as a function of irradiance,spectrum, and cell temperature

We describe here a lumped diode model for concentrator multijunction solar cells, in which the temperature, irradiance and spectrum dependences are explicitly included. Moreover an experimental method based on it for the prediction of the I‐V curve under any irradiance‐spectrum‐temperature conditions from a single input measurement is proposed and applied to a set of commercial triple‐junction solar cells in order to demonstrate its validity. Component ‘isotype’ cells are used as reference cells for intensity and spectrum, sparing the measurement of light spectrum and cell spectral response. Finally, a mean RMS prediction error of 0.85% over a range of 100X‐25°C to 700X‐75°C is reported for the whole set when the model parameters inherent in the cell are assumed to be the same for every sample. If optimum parameters are extracted for every cell, the RMS error is reduced to 0.53%. Copyright © 2010 John Wiley & Sons, Ltd.     

Explanation for the dark I–V curve of III–V concentrator solar cells

The measurement of the dark I–V curve is one of the most straightforward methods for characterizing solar cells. Consequently, an accurate knowledge of its meaning is of high relevance for the comprehension and technological feedback of these devices. In this paper, an explanation of the dark I–V curve for concentrator III–V solar cells is presented using a 3D (three‐dimensional) model in order to provide a proper data fit that provides meaningful physical parameters that are also compatible and coherent with a data fit from illumination curves. The influence on the dark I–V curve of the most significant series resistance components of concentrator solar cells is also analysed concluding that only the vertical component as well as the front contact‐specific resistance can be assessable by means of this characterization method while both emitter and metal sheet resistances cannot be detected. For comparison purposes, the same experimental data have been fitted by means of a traditional two‐diode model showing that, although an accurate dark I–V curve fitting can be achieved, the extracted parameters are unable to reproduce illumination data since lumped models assume the same ohmic losses distribution for both dark and illumination conditions. Copyright © 2007 John Wiley & Sons, Ltd.     

Intermediate-band solar cells based on dilute alloys and quantum dots

This paper describes our recent developments of intermediate-band solar cells, with a focus on the use of dilute alloys and nanostructured materials such as quantum dots (QDs). The concept of"full-spectrum" solar cells and their working mechanism with various material structures based intermediate-band solar cells, including material growth, structural and chemical analysis, device modeling and testing, are presented. Finally, the progress and challenges of quantum-dot-based solar cells are discussed.     

Influence of temperature on luminescent coupling and material quality evaluation in inverted lattice‐matched and metamorphic multi‐junction solar cells

Inverted metamorphic multi‐junction solar cells have reached efficiencies close to 46%. These solar cells contain very high‐quality materials that exhibit strong luminescent coupling between the junctions. The presence of luminescent coupling has a significant impact on the behavior of multi‐junction solar cells affecting the optimal design of these devices. Because of the importance of studying devices under real operating conditions, the temperature dependence of the luminescent coupling is analyzed over a range of 25–120°C. Luminescent coupling analysis results show a reduction of the luminescent coupling current as a function of temperature in two tandem components of an inverted metamorphic triple junction solar cell such as GaInP/GaAs and GaAs/GaInAs solar cells. This reduction is quantified and examined by means of luminescent coupling analysis and modeling, electroluminescence measurements and optical modeling at the device and subcell level. The results of the models are verified and discussed. Copyright © 2015 John Wiley & Sons, Ltd.     

Assessing material qualities and efficiency limits of III–V on silicon solar cells using external radiative efficiency

The paper presents a quantitative approach to the investigation and comparison of the material qualities of III–V on silicon (III–V/Si) solar cells by using external radiative efficiencies. We use this analysis to predict the limiting efficiencies and evaluate the criteria of material quality in order to achieve high‐efficiency III–V/Si solar cells. This result yields several implications for the design of high‐efficiency III–V/Si solar cells. Copyright © 2016 John Wiley & Sons, Ltd.     

高效率量子点中间带太阳电池的构建与实现

中间带太阳电池是为了充分利用太阳光谱中的红外光子能量而提出的一种高效率新概念太阳电池。介绍了中间带太阳电池的能量上转换原理、量子点中间带的物理优势、量子点中间带太阳电池的结构组态和理论转换效率。评述了它的近期研究进展,并提出了发展这种新概念太阳电池的若干技术对策,其中包括补偿量子点的积累应变、优化量子点的生长参数和选择新的量子点结构。最后指出,由于应变的补偿,有序量子点层的形成以及新量子点结构的采用使太阳电池的光伏性能得以有效改善。可以预期,具有高转换效率的量子点中间带太阳电池的构建与实现将会对未来的光伏技术与产业带来革命性的影响。     

New approach for forming bulk-heterojunction solar cells comprising a π-conjugated polymer and C60

A new approach for high-efficiency polymer solar cells utilizing a BHJ active layer consisting of poly(3-hexylthiophene) (P3HT) as a donor and buckminsterfullerene, C₆₀ as an acceptor was demonstrated. P3HT/C₆₀ BHJ films were made possible by in situ formation of C₆₀ from solubilized addends, C₆₀–CpCO₂R (R = Hex, Oct, and EHex) by retro Diels–Alder reaction at, or above, 100 °C. These cells exhibit enhanced performances compared to as-prepared P3HT/C₆₀ BHJ films, showing better morphology.     

Characterization of the spatial distribution of irradiance and spectrum in concentrating photovoltaic systems and their effect on multi‐junction solar cells

The irradiance and spectral distribution cast on the cell by a concentrating photovoltaic system, typically made up of a primary Fresnel lens and a secondary stage optical element, is dependent on many factors, and these distributions in turn influence the electrical performance of the cell. In this paper, the effect of spatial and spectral non‐uniform irradiance distribution on multi‐junction solar cell performance was analyzed using an integrated approach. Irradiance and spectral distributions were obtained by means of ray‐tracing simulation and by direct imaging at a range of cell‐to‐lens distances. At the same positions, I–V curves were measured and compared in order to evaluate non‐uniformity effects on cell performance. The procedure was applied to three different optical systems comprised a Fresnel lens with a secondary optical element consisting of either a pyramid, a dome, or a bare cell. Copyright © 2011 John Wiley & Sons, Ltd.