Researchers say this work represents a major leap forward in understanding and developing sustainable energy solutions. In the future, this innovative approach will redefine the efficiency and accessibility of solar energy.
The improved efficiency of this material is largely attributed to its unique "intermediate band states," which are specific energy levels located within the material's electronic structure. This makes it an ideal choice for solar energy conversion.
These states are located within the optimal subband gap (the energy range in which the material can effectively absorb sunlight and generate charge carriers), approximately 0.78 to 1.26 electron volts. Furthermore, the material exhibits high absorption levels in the infrared and visible regions of the electromagnetic spectrum.
In traditional solar cells, the maximum EQE is 100%, meaning that each photon absorbed from sunlight generates and collects one electron. However, some advanced materials and structures developed in recent years have demonstrated the ability to generate and collect multiple electrons from high-energy photons, meaning that the EQE can exceed 100%. Although such multiple exciton generating materials are not yet widely commercialized, they have the potential to greatly improve the efficiency of solar energy systems.
In this new material, "intermediate band states" can capture the photon energy lost in traditional solar cells. Researchers developed this novel material using "van der Waals gaps," which are atomically small gaps between layered two-dimensional materials. These gaps can confine molecules or ions, and materials scientists often use them to insert or embed other elements to tune material properties.
To develop new materials, researchers intercalated zero-valent copper atoms between layers of a two-dimensional material composed of germanium selenide and tin sulfide. They then developed a prototype serving as a proof-of-concept. The results showed that its rapid response and improved efficiency strongly demonstrate the potential of copper intercalation as a quantum material in photovoltaic applications, providing a new avenue for improving solar energy conversion efficiency.
