Energy Level Tuning in CsPbBr₃ Perovskite Solar Cells through In Situ-Polymerized PEDOT Hole Transport Layer.

Area of Science:

• Materials Science
• Renewable Energy
• Photovoltaics

Background:

• All-inorganic CsPbBr3 perovskite solar cells offer stability and low cost.
• Limited power conversion efficiency (PCE) is due to the lack of a hole transport layer (HTL) and a significant energy level mismatch.
• This mismatch occurs between the CsPbBr3 highest occupied molecular orbital (HOMO) and the carbon electrode's work function.

Purpose of the Study:

• To enhance the PCE of CsPbBr3 perovskite solar cells.
• To address the energy level difference issue by introducing an in situ polymerized hole transport layer.
• To improve hole extraction and transport between the perovskite layer and the carbon electrode.

Main Methods:

• Spin-coating of 2,5-dibromo-3,4-ethylenedioxythiophene (DBEDOT) monomer onto CsPbBr3 films.
• In situ polymerization of DBEDOT to poly(3,4-ethylenedioxythiophene) (PEDOT) via annealing.
• Fabrication and testing of perovskite solar cell devices with and without the PEDOT layer.

Main Results:

• The in situ polymerized PEDOT layer effectively reduced the energy level difference between CsPbBr3 and the carbon electrode.
• Power conversion efficiency (PCE) was enhanced, reaching a maximum of 9.81% for the PEDOT-based device.
• Unencapsulated devices demonstrated excellent stability, retaining 95.9% of their initial efficiency after 40 days.

Conclusions:

• In situ polymerization of DBEDOT to form a PEDOT HTL is a viable strategy to boost PCE in CsPbBr3 perovskite solar cells.
• This method successfully mitigates the energy level mismatch, improving charge transport.
• The developed devices exhibit promising efficiency and stability for photovoltaic applications.