Intraband transitions at a CsPbBr₃/GaAs heterointerface in a two-step photon upconversion solar cell

Area of Science:

• Materials Science
• Renewable Energy
• Semiconductor Physics

Background:

• Two-step photon upconversion solar cells (TPU-SCs) utilize III-V semiconductors for enhanced sub-bandgap photon absorption via intraband transitions.
• The integration of perovskite materials offers potential for novel heterointerface functionalities in solar cell applications.

Purpose of the Study:

• To investigate the feasibility of achieving intraband transitions at perovskite/III-V semiconductor heterointerfaces for TPU-SCs.
• To demonstrate a novel CsPbBr₃/GaAs heterointerface-based TPU-SC and evaluate its performance.

Main Methods:

• Fabrication of a CsPbBr₃/GaAs heterointerface for a two-step photon upconversion solar cell.
• Experimental analysis of short-circuit current (J_SC) and open-circuit voltage (V_OC) under varying illumination conditions, including sub-bandgap photons.
• Investigation of excitation power dependence to elucidate the underlying enhancement mechanisms.

Main Results:

• The CsPbBr₃/GaAs-based TPU-SC demonstrates an ideal theoretical energy conversion efficiency of 48.5%, surpassing that of Al_0.3Ga_0.7As/GaAs-based devices by 2.1%.
• Experimental results show increased J_SC and V_OC upon illumination with sub-bandgap photons.
• An adiabatic optical process at the CsPbBr₃/GaAs heterointerface was identified as the mechanism for J_SC enhancement, involving efficient pumping of accumulated electrons.

Conclusions:

• The CsPbBr₃/GaAs heterointerface enables efficient two-step photon upconversion, leading to enhanced solar cell performance.
• This work highlights the potential of perovskite/III-V semiconductor heterostructures for developing next-generation, high-efficiency single-junction solar cells.