Schematic of the solar cell
A novel project led by Mexico's Autonomous University of Querétaro has broken new ground in solar energy research. For the first time, they explored the creation of thin-film solar cells using a unique absorber composed of silver, barium, titanium, and selenium (Ag2BaTiSe4).
The research centered on examining various aspects of the absorber, like electron affinity, surface defects, and unwanted resistance. Their goal was to understand how these elements affect the solar cell's efficiency. To find eco-friendlier options than the commonly used cadmium sulfide (CdS), the team experimented with different buffer layers.
Utilizing the SCAPS-1D software from the University of Ghent, the researchers simulated this innovative solar cell design. The design included layers of molybdenum diselenide (MoSe2) and Ag2BaTiSe4 on a glass substrate, topped with various buffer materials, and finished with conductive films and a metal contact.
In their pursuit of alternative buffers, they considered CdS and new compounds like magnesium, calcium, strontium, and barium sulfide. The team meticulously evaluated factors like layer thickness and carrier concentration.
They introduced neutral defects at crucial junctions in their model to mimic real-life conditions and studied how these affected the cell's performance. Impedance spectroscopy was used to analyze charge accumulation at the cell interface.
Their findings were promising. With an optimal carrier concentration for MoSe2 and a specific absorber thickness, they achieved efficiencies up to 18.84% with a magnesium sulfide layer and even higher with other materials. Adjusting MoSe2 parameters and interface properties could potentially push efficiencies to around 30%.
The research highlighted the significant role of interface defects, often caused by structural inconsistencies and metal diffusion during manufacturing. They suggested layer deposition techniques, etching, heat treatments, and passivation layers to minimize these defects.
Published in the journal Scientific Reports, their study, titled "Highly efficient emerging Ag2BaTiSe4 solar cells using a new class of alkaline earth metal-based chalcogenide buffers alternative to CdS," points towards exciting new directions in photovoltaic research. By using Ag2BaTiSe4 as an absorber and exploring non-toxic buffer alternatives, this research opens doors to creating highly efficient, environmentally friendly thin-film solar cells.