New Abundant Material Raises Solar Cell Efficiency by Capturing Heat Loss

Conventional silicon solar cells lack the mechanism to capture highly charged electrons

April 19, 2023


Colorado State University (CSU) researchers said introducing molybdenum disulfide (MoS2) in solar cells can help capture excess solar energy, which is generally lost as heat, thereby improving light-to-energy efficiency conversion.

They performed a series of experiments using laser spectroscopy while capturing the hot carriers or highly charged electrons.

The team claimed that conventionally used silicon solar cells do not provide ways for such hot carrier extraction phenomenon, which proves to be an efficient method to increase the overall efficiency of the solar cells.

The improved crystalline structure of MoS2 enables the material to extract and exploit the energy of so-called hot carriers, which are highly energetic electrons. The researchers briefly excite these hot carriers from their ground states by hitting them with sufficient light.

Rather than losing the highly charged electrons as heat, the team could successfully convert the energy from those hot carriers into photocurrent by exciting the electrons in the material.

The experiments replaced the broadly used silicon with 2-dimensional ultrathin films of molybdenum disulfide using ultrafast laser spectroscopy and ultrafast pump-probe transient absorption spectrometer.

The study titled ‘Hot carrier extraction from 2D semiconductor photoelectrodes’ was published in the Proceedings of the National Academy of Sciences.

Given the improved light absorption capabilities, the researchers observed that MoS2 could be a possible alternative to silicon in solar cells.

The scientists used a pump-probe spectrometer to further study the energy state of each electron when excited with a laser pulse.

The pump-probe transient absorption spectrometer allowed them to capture snapshots of charge flow in their device.

The team created a photoelectrochemical cell using a single atomic layer of MoS2 and used the pump-probe technique to track the cooling of electrons as they moved through the material.

In another research, scientists at the U.S. National Renewable Energy Laboratory developed a new tin-lead perovskite tandem cell merging different layers of two chemical compounds achieving a power conversion efficiency (PCE) of 25.5%.

Last year, a group of researchers developed a method to help achieve a 25% increase in energy levels absorbed by wafer-thin solar photovoltaic panels. They claimed that their solar panels, just one micrometer thick (1μm), convert light into electricity more efficiently than others as thin and pave the way to make it easier to generate more clean, green energy.