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In order to increase the photocurrent of tandem solar cells with a silicon (Si) solar cell as the bottom cell, we investigate the relationship between the localized surface plasmon resonance effect of gold nanoparticles (AuNPs) and the arrangement of AuNPs onto solar cells. AuNPs were deposited on P-type crystalline Si (c-Si) cells and Si heterojunction (SHJ) type cells. To obtain the localized surface plasmon resonance effect, the shape, size, and arrangement of the nanostructures are important. Especially, arrangement of AuNPs onto solar cells was inquired in this study because these parameters must be adjusted appropriately to produce a plasmon resonance in a specific wavelength range. It was found that the plasmon resonance effect is significant when deposited on the surface of c-Si cell rather than on top of the Ag electrode. AuNPs deposition on the c-Si cell surface leads to not only the localized surface plasmon resonance effect but also improvement in charge transport between the c-Si cell surface and Ag electrode. However, in the SHJ-type cells, the plasmon resonance effect was not observed because the surface layer was composed of a W-doped In2O3 (IWO) layer. [ABSTRACT FROM AUTHOR]

This paper particularly explains potential-induced degradation (PID) of wafer-based standard p-type crystalline silicon technology. We present a single-encapsulation method that is useful for simulating PID in the laboratory to facilitate microanalyses of module-level solar cells. The PID testing is performed for the module with single-encapsulation and conventional modules. Their current–voltage characteristics and electroluminescence images are investigated before and after the PID tests. As described herein, we infer that the single-encapsulation modules generate PID almost in the same way as conventional modules do, and that the degradation trend is almost identical to that of conventional modules. Results of PID recovery tests indicate that the time necessary for PID recovery is always less than that for PID generation, irrespective of the encapsulation method. [ABSTRACT FROM AUTHOR]

This study investigated how the SiNx refractive index (RI) and SiO2 thickness, dox, of stacked SiNx/SiO2 passivation layers of the front p+emitters of n‐type crystalline‐silicon (c‐Si) photovoltaic (PV) cells affect their polarization‐type potential‐induced degradation (PID) behaviors. We prepared six n‐type c‐Si PV cells with an RI of 2.0 or 2.2 and with dox of 9, 2, or 1 nm. Then PV modules fabricated from the cells were subjected to PID tests during which a bias of −1000 V was applied to cells with respect to the front cover glass surface. For dox of 9 or 2 nm, rapid polarization‐type PID was observed, irrespective of the RI. However, for dox of 1 nm, the RI markedly affected the degradation behavior, and cells with an RI of 2.2 showed no degradation. These findings are attributable to carrier transport between the high RI (Si‐rich) SiNx and the c‐Si substrates, which can readily occur only when the SiO2 layer is sufficiently thin for electrons to tunnel through the SiO2 layer. These results are important for elucidating polarization‐type PID mechanisms and for developing preventive measures against polarization‐type PID. [ABSTRACT FROM AUTHOR]

We investigate the effect of temperature and pre-annealing on the potential-induced degradation (PID) of silicon heterojunction (SHJ) photovoltaic (PV) modules. SHJ PV modules show a faster decrease in short-circuit current density (J sc) at higher temperatures during PID tests. We also observe a complex relationship between the degree of the J sc decrease and temperature during the PID tests. Pre-annealing before the PID tests at sufficiently high temperatures leads to the complete suppression of the PID of SHJ PV modules. The decrease in J sc is known to be due to the chemical reduction of indium (In) in transparent conductive oxide (TCO) films in SHJ cells, in which water (H2O) in SHJ modules is involved. These indicate that H2O may out-diffuse from the SHJ PV modules during a PID test or pre-annealing at sufficiently high temperatures, by which the chemical reduction of indium in TCO to metallic In is suppressed. [ABSTRACT FROM AUTHOR]

An optical pH sensor that enables the non-destructive measurement of acetic acid and its distribution in a photovoltaic module during damp heat (DH) testing is reported. The sensor was fabricated by impregnating a solution of a pH-sensitive fluorescent dye into a fluororesin membrane filter, which was then dried. While conducting the DH test, fluorescence spectra from 20 pH sensors were periodically recorded and converted into pH values using a predetermined calibration curve. As a result, we succeeded in measuring changes in pH with a DH test time of up to 2000 h, and it was possible to obtain information on the pH distribution in the module. We also confirmed no change in pH in a module with a silicone encapsulant free from acetic acid, and revealed that the sensor that we developed does not respond to moisture and heat, but only to acetic acid. [ABSTRACT FROM AUTHOR]

n‐Type crystalline‐silicon (c‐Si) photovoltaic (PV) cell modules attract attention because of their potential for achieving high efficiencies. The market share of n‐type c‐Si PV modules is expected to increase considerably, with wide use in PV systems, including large‐scale PV systems, for which the system bias is set as markedly high. Such a high system bias leads to performance losses known as potential‐induced degradation (PID). By virtue of many researchers' efforts, the PID behaviors, mechanisms, and preventive measures against PID have been well documented in conventional p‐type c‐Si modules. Researchers recently started to investigate PID in high‐efficiency c‐Si solar cells including n‐type c‐Si PV modules. Yet, the understanding of PID phenomena remains incomplete. Herein, a literature review of PID in high‐efficiency n‐type c‐Si PV modules is provided as a resource elucidating the current status of related research and remaining unresolved issues. This report mainly presents discussion of PID in several kinds of n‐type c‐Si PV modules in terms of materials science. PID phenomena are described as divided into some degradation modes. Details present a review of their respective degradation modes, degradation behaviors, proposed mechanisms, and potential measures against degradation. Remaining open issues and anticipated future studies are also summarized. [ABSTRACT FROM AUTHOR]

A hexagonal boron nitride thin film was prepared on a c-plane sapphire substrate at a substrate temperature of 1200 °C and a reactor pressure of 5 kPa by chemical vapor deposition using BCl3 as a boron source. The film, consisting of columnar grains with flat top surfaces, grew epitaxially on the substrate. This sample showed pronounced intrinsic exciton cathodoluminescence (CL) at 215 nm at room temperature, although broad emission at around 350 nm was dominant. Note that the spectrum shape in the band edge region closely matched that observed for a high-quality bulk crystal in terms of peak wavelength and width. The CL images of the surface revealed the correlation between the film structure and the luminescence property, where the intrinsic excitonic luminescence was exhibited only from the columnar grains, whereas the impurity- and/or the defect-related emissions were observed mainly from surface defects with randomly oriented grains. [ABSTRACT FROM AUTHOR]