Critical Evaluation of the Foundations of Solar Simulator Standards

Sinton, Ronald A.; Wilterdink, Harrison; Dinger, Justin; Blum, Adrienne L.; Dobson, Weston; Sainsbury, Cassidy

doi:10.1109/pvsc.2017.8366399

Cited by 4 publications

(1 citation statement)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Todos os dispositivos estudados nesta tese foram caracterizados através de curvas corrente-tensão com iluminação e no escuro utilizando um simulador solar. Simuladores solares são padronizadamente classificados atribuindo-se uma classe (A, B, ou C) para cada uma das três principais características da radiação que produzem, a saber: correspondência espectral, inomogeneidade de irradiância e estabilidade temporal [140]. A tabela 3 mostra os critérios para a atribuição das classes.…”

Section: Simulador Solarunclassified

Viabilidade e desenvolvimento de células solares de banda intermediária baseadas em GaAs com pontos quânticos de submonocamada de InAs/GaAs

Santos¹

View full text Add to dashboard Cite

Our objective is to assess the viability of GaAs-based intermediate band solar cells grown by molecular beam epitaxy using InAs/GaAs submonolayer quantum dots to create intermediate bands. This work is divided into two parts. In the first one, given that epitaxial III-V solar cells are a scarce technology in Brazil and that the photovoltaics research program is new in our research group, we developed conventional GaAs solar cells. We combined theoretical analyses using SCAPS and OpenFilters software with experimental analyses using current-voltage method, spectrophotometry (reflectance) and spectroscopic ellipsometry. This allowed us to produce a device with 17.2 % efficiency operating under 298 K and AM1.5G illumination. We discussed in detail the design of a TiO 2 /Al 2 O 3 antireflective coating that led our best device to achieve a short-circuit current density of 23,6 mA/cm 2 . In the second part, we discussed the workings of quantum dot solar cells. We observed that InAs/GaAs submonolayer quantum dots led to more efficient solar cells relative to those having Stranski-Krastanov quantum dots, as the latter cause a much higher open-circuit voltage degradation than the former. However, the submonolayer quantum dots did not lead to devices more efficient than conventional ones. Through Schrödinger-Poisson calculations in the effective-mass approximation with NextNano software, we concluded that this shortfall is probably due to the submonolayer quantum dots not being able to confine electrons in three dimensions as required by the intermediate band solar cell model. The calculations indicate that the nanostructures need to be larger and have a higher In concentration to allow such electron confinement. Lastly, using atom probe tomography, we identified growth conditions that lead to a higher In concentration in submonolayer quantum dots relative to the ones we applied to our devices. Such growth conditions might be explored in the future to achieve true intermediate band solar cells.

show abstract

Section: Simulador Solarunclassified

Viabilidade e desenvolvimento de células solares de banda intermediária baseadas em GaAs com pontos quânticos de submonocamada de InAs/GaAs

Santos¹

View full text Add to dashboard Cite

show abstract

Comprehensive Performance Calibration Guidance for Perovskites and Other Emerging Solar Cells

Song

Friedman

Kopidakis

2021

Advanced Energy Materials

View full text Add to dashboard Cite

have also shown remarkable efficiency improvements from ≈10% in 2017 to the latest confirmed efficiency records of 18.2% and 18.1%, respectively. [1,2] Despite the progress, researchers [3][4][5][6][7][8] have argued that many reported efficiencies in journals are being incorrectly measured, which can lead to controversies in efficiency comparison, and damage the credibility and long-term development of this field. The most common cause of efficiency ambiguity is related to the electrical I-V measurement procedure. For conventional crystalline Si cells, a current-voltage (I-V) scan is usually carried out with short dwell times from milliseconds (hereafter termed "flash I-V") to seconds (hereafter termed "fast I-V"). It is a very robust method to extract device efficiencies for Si PV and has been included in the ASTM and IEC standards [9,10] for both PV cell and module performance measurements. However, adoption of this protocol for emerging PV technologies causes efficiency ambiguity due to variable forms of electrical behaviors, mostly relating to the I-V sweep setup (i.e., scan rate and direction) and preconditioning requirements like lightsoaking. [4][5][6][7][8] For instance, hysteresis behaviors in fast I-V scans are often seen in perovskite solar cells, as shown in Figure 1. The I-V curves differ between the forward and reverse scan directions and the degree of discrepancy typically varies with the scan rate and/or preconditioning. It is therefore difficult to conduct meaningful efficiency comparisons between different emerging PV device architectures using conventional fast I-V scans. What is more important is that these controversial performance results may sacrifice confidence on future emerging PV deployment in the renewable energy portfolio. Alternatively, measurement protocols that drive the cell to steady-state provide a reliable and reproducible way to calibrate efficiencies and help all interest groups set up benchmarks for performance comparison and technology advancement. A detailed discussion on the steady-state performance calibration protocol will be presented in Section 2.3 and is the main scope of this paper.Prior to discussing steady-state performance measurements and in the interest of providing a comprehensive calibration protocol for emerging PV, we also briefly discuss two important aspects of the performance measurement sequence: the area definition and the spectral response measurement. Poorly defined device areas [11,12] result in a common measurement error and are discussed in Section 2.1. Given the small sizes

show abstract