Lehigh University researchers have created a revolutionary solar cell material with an external quantum efficiency of up to 190%, surpassing traditional efficiency limits and holding great promise for improving future solar energy systems. Further development is required for practical application supported by a grant from the US Department of Energy.
This shows great potential for the development of highly efficient next-generation solar cells, which are vital to meet global energy demand.
A team from Lehigh University has created a material that could significantly increase the efficiency of solar panels.
Using the material as an active layer in a solar cell, the prototype exhibits an average photovoltaic absorption of 80%, a high generation rate of photo-excited carriers, and an unprecedented external quantum efficiency (EQE) of up to 190%—far exceeding this benchmark. the theoretical Shockley-Queisser efficiency limit for silicon-based materials and pushes the field of quantum materials for photovoltaics to new heights.
Chindeu Ekuma. Credit: Lehigh University
“This work represents a significant leap forward in understanding and developing sustainable energy solutions, highlighting innovative approaches that could redefine the efficiency and affordability of solar energy in the near future,” said Chinedu Ekuma, professor of physics. of the article in Science Advances with Lehigh doctoral student Srihari Kastuar.
Advanced Material Properties
The material’s efficiency jump is largely due to its distinct “gap states,” specific energy levels within the material’s electronic structure that make it ideal for solar energy conversion.
These states have energy levels within their optimal subband gaps—energy ranges where the material can efficiently absorb sunlight and produce charge carriers—about 0.78 and 1.26 electron volts.
In addition, the material performs particularly well with high levels of absorption in the infrared and visible regions of the electromagnetic spectrum.
Schematic of a thin-film solar cell with CuxGeSe/SnS as the active layer. Credit: Ekuma Lab / Lehigh University
In conventional solar cells, the maximum EQE is 100%, which represents the generation and accumulation of one electron for every photon absorbed from sunlight. However, some advanced materials and configurations developed over the past few years have demonstrated the ability to generate and harvest multiple electrons from high-energy photons, representing an EQE greater than 100%.
Srihari Kastuar, Lehigh University. Credit: Lehigh University
Although not yet widely commercialized, Multiple Exciton Generation (MEG) materials have the potential to significantly increase the efficiency of solar energy systems. In the material developed by Lehigh, the intermediate band states allow the capture of photon energy lost by traditional solar cells, including by reflection and heat generation.
Material development and potential
The researchers developed the new material using “van der Waals gaps,” atomically small gaps between layered two-dimensional materials. These voids can confine molecules or ions, and materials scientists typically use them to introduce or “intercalate” other elements to tune material properties.
To develop their new material, the Lehigh researchers sandwiched zero-valent copper atoms between layers of a two-dimensional material made of germanium selenide (GeSe) and tin sulfide (SnS).
Ekuma, an expert in computational condensed matter physics, developed the prototype as a proof of concept after extensive computer modeling of the system showed theoretical promise.
“Its fast response and enhanced efficiency show the potential of Cu-intercalated GeSe/SnS as a quantum material for use in powerful photovoltaic applications and offer a way to increase efficiency in solar energy conversion,” he said. “It is a promising candidate for the development of next-generation, high-efficiency solar cells that will play a crucial role in meeting global energy needs.”
While integrating the newly designed quantum material into current solar energy systems will require further research and development, Ekuma notes that the experimental techniques used to create these materials are already highly advanced. Over time, scientists have mastered a method that precisely embeds atoms, ions, and molecules into materials.
Citation: Srihari M. Kastuar and Chinedu E. Ekuma, 10 April 2024, Science Advances.
DOI: 10.1126/sciadv.adl6752
The research was funded in part by a grant from the US Department of Energy.