Progress in Photovoltaics最新文献

The finite difference time domain (FDTD) method has been used to model the optical properties of ZnO/Ag/ZnO (ZAZ) multilayer structure. We proposed two configurations: a 5- to 15-nm-thick ZnO dense layer (DL) and ZnO nanoparticle (NP) coatings in monolayer, bilayer, and trilayer around Ag nanowire (AgNW) with a 30-nm diameter. The configurations were designed to improve the ZAZ electrode performance in organic photovoltaics (OPVs). The plasmonic resonance behavior of ZnO coated AgNW was analyzed in air and later incorporated into a ZAZ electrode with PM6:Y6 (active layer), yielding excellent plasmonic results for both configurations. Our results further reveal that ZnO DL coatings offer superior field confinement, while ZnO NP coating shows promising light-scattering capabilities, particularly beneficial for maximizing energy transfer to the active layer in OPV devices. The experimental transmission spectra of ZAZ electrodes closely align with the theoretical model, confirming their accuracy. Integrating ZnO NP layers into ZAZ electrodes with strong plasmonic performance offers promising potential for enhancing light absorption in the photoactive layer and improved device efficiency.

Sinha, A, Qian, J, Moffitt, S L, Hurst, K, Terwilliger, K, Miller, D C, Schelhas, L T, and Hacke, P. UV-Induced Degradation of High-Efficiency Silicon PV Modules With Different Cell Architectures. Prog Photovolt Res Appl. 2023; 31(1): 36–51, https://doi.org/10.1002/pip.3606.

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Fast and accurate performance analysis of fielded solar modules is essential for the reliable, long-term operation of large-scale solar farms. Daylight photoluminescence imaging has emerged as a promising inspection method, providing quantitative information while circumventing many logistical constraints associated with alternative methods. Luminescence images of modules acquired with partial current extraction reveal series resistance defects, a key contributor to cell and module degradation. A novel method is presented to estimate the reduction in output power caused by series resistance defects, based purely on daylight photoluminescence image data. This automated process generates electrical models to match series resistance-related intensity variations observed in daylight photoluminescence images, which are used to quantify performance losses. Cell-level simulations and experimental results are presented, yielding excellent results, as well as promising proof-of-concept demonstrations on full modules.

A recent trend in commercial PV modules is a transition to n-type silicon cells, including passivated emitter rear totally diffused (n-PERT), tunnel oxide passivated contact (TOPCon), and silicon heterojunction (SHJ). There is evidence via lab studies that some of these cells are more susceptible to UV induced degradation (UVID), yet there is a lack of confirmation that such degradation occurs in the field. Current IEC standards designed to screen for early module failures require only minimal UV exposure (15 kWh/m² 280–400 nm, ~2–3 months equivalent outdoor exposure). Here, we investigate fielded n-PERT silicon (Si) modules from a commercial utility that show power losses of ~2%/year. We present a comprehensive picture of the physics and chemistry of degradation supported by both module and cell electronic characterization (EL, PL, IV, EQE, and DLIT) and materials-level morphological and chemical analysis (SEM, EDS, XPS, FTIR, and HPLC). All sampled site modules show short circuit current (I_sc) and open circuit voltage (V_oc) losses when compared to unfielded spares, with the most severely degraded also having losses in fill factor (FF). We identify two different degradation modes contributing to overall power loss: (1) external quantum efficiency (EQE) measurements show losses in the blue range of the spectra, indicative of cell surface recombination losses, and (2) variations in high series resistance (R_s) at the cell level that are correlated with compositional differences in cell metallization. Using unfielded spares, we were able to reproduce V_oc, I_sc, and EQE losses via a minimum UV stress of 67.5 kWh/m² (280–400 nm), 4.5× the exposure currently required in IEC 61215-2 (MQT 10). Degradation continued with additional UV dosage equivalent to the fielded modules (405 kWh/m² total), with power loss leveling out at an average of 6.1%. Subsequent 1000 h of 85% RH/85°C damp heat testing showed that cells exposed to UV underwent additional severe series resistance degradation, even those without the susceptible paste composition seen in the field, whereas non-UV exposed cells saw little change. We attribute this to higher concentrations of acetic acid generated on the UV exposed area of the module, leading to degradation of the gridline/cell interface and high R_s. This study is unique in that it reproduces field observed utility scale UVID with an accelerated test and supports the need for standards development for longer UV exposure combined with other stress factors to catch materials interplay within a module package.