| Work Detail |
Developed by Korean scientists, the so-called ACIGS cell is intended for applications in perovskite-CIGS tandem photovoltaic devices. Their work demonstrates correlations between the diffusion behavior of elements and the formation of notch points in ACIGS films.
Researchers at South Koreas Daegu-Gyeongbuk Institute of Science and Technology (DGIST) have developed a silver-alloyed photovoltaic cell based on copper-indium-gallium-selenium (CIGS) thin-film technology that they claim can achieve a remarkable power conversion efficiency of 17.7% without applying post-deposition treatments or anti-reflective coatings.
The scientists explained that silver alloy CIGS (ACIGS) photovoltaic devices require a production process that requires lower evaporation temperatures and allows for smaller energy band gaps.
“This research aims to explore the impact of manufacturing conditions, such as processing temperature or the amount of silver (Ag) added,” they stated. “Our goal is to improve the current density to manufacture high-efficiency perovskite/CIGS tandem solar cells with the potential to achieve efficiencies greater than 30%.”
The research group manufactured different cell samples, in which copper (Cu) and selenium (Se) were evaporated at substrate temperatures ranging between 340 ºC and 470 ºC. The manufacturing process, in all samples, began with an ultrathin layer of Ag. Next, a three-stage coevaporation process began. In its first stage, indium (In), gallium (Ga) and Se were supplied at a temperature of approximately 340 ºC.
The second stage consisted of evaporating Cu and Se at substrate temperatures between 340 ºC and 470 ºC until a Cu-rich CIGS phase was formed. In the third and final stage, In, Ga and Se were evaporated on the substrate at the same temperature as in the second stage.
After completing the three-step process, the films were evaluated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and scanning transmission electron microscopy (STEM) combined with energy-dispersive X-ray (EDX) analysis. .
The scientists fabricated the cell with a glass substrate, a molybdenum trioxide (MoO3) buffer layer, the ACIGS absorber, a cadmium sulfide (CdS) buffer layer, a zinc oxide (i-ZnO) window layer, and a window layer of aluminum doped ZnO (AZO).
Tested under standard lighting conditions, the cell, processed at a temperature of 340ºC, achieved an efficiency of 15.4%.
When processed at temperatures of 440°C, the device achieved a power conversion efficiency of 17.7%. “The short circuit density of the cell can be controlled by the processing temperature in the ACIGS configuration,” they stated. “These results underscore the importance of understanding deposition temperature and its impact on the properties of ACIGS films, paving the way for further advances in solar cell technology.”
The solar cell design was presented in the article “ Exploring the deposition pathway in the notch region of double-graded bandgap ACIGS solar cells. ” ), published in the Journal of Science: Advanced Materials and Devices . “This study demonstrates correlations between the diffusion behavior of elements and the formation of the notch point in ACIGS films, which ultimately influence the resulting current loop voltage and fill factor,” the scientists conclude. |
