An international research team has successfully demonstrated the technical feasibility of solar cells utilizing absorbers composed of silver, barium, titanium, and selenium (Ag2BaTiSe4).
The research, led by the Autonomous University of Querétaro in Mexico, marks the first proposal for fabricating thin-film solar cells with this particular absorber material.
The approach involved a thorough analysis of the absorber’s electron affinity, interfacial defects, and parasitic resistance, along with the evaluation of different buffer layer materials to replace cadmium sulfide (CdS).
The team utilized the SCAPS-1D solar cell capacitance software from the University of Ghent for simulating the novel cell design, incorporating a range of layers such as molybdenum (Mo)-coated glass substrate, molybdenum diselenide (MoSe2) layer, Ag2BaTiSe4 absorber, buffer layer, transparent conductive oxide films (Indium Zinc Oxide and Aluminum-doped Zinc Oxide), and metal contact.
For the buffer layers, alternatives like magnesium sulfide (MgS), calcium sulfide (CaS), strontium sulfide (SrS), and barium sulfide (BaS) were considered, taking into account critical parameters like thickness, carrier concentration, and defect density.
The team introduced neutral defects at specific interfaces to replicate realistic operating conditions and utilized impedance spectroscopy to investigate charge carrier accumulation at the cell interface.
Their analysis indicated optimal values for MoSe2’s carrier concentration and the thickness of the Ag2BaTiSe4 absorber. The solar cell exhibited varying power conversion efficiencies with different buffer layers, with the highest achieved efficiency being 20.87% using a BaS layer.
Further analysis showed that by fine-tuning parameters and interfacial properties, efficiencies could potentially reach up to 30.23%.
The researchers emphasized the significant impact of interface defects on cell performance, attributing these defects to structural issues between layers and metal cation diffusion during fabrication.
They suggested employing effective deposition techniques and methods such as etching, post-heat treatment, and passivation layer insertion to minimize these defects.
The study, titled “Highly efficient emerging Ag2BaTiSe4 solar cells using a new class of alkaline earth metal-based chalcogenide buffers alternative to CdS,” has been published in scientific reports.
The researchers believe their findings could pave the way for the photovoltaic community to develop highly efficient thin-film solar cells using Ag2BaTiSe4 as an absorber and new alkaline earth metal chalcogenides as non-toxic buffer alternatives. The research team also included academics from the Bangladesh Atomic Energy Commission.
