A Two-Step Top Surface Passivation Strategy for n-i-p Wide-Band Gap Perovskite Solar Cells

Area of Science:

• Materials Science
• Renewable Energy
• Photovoltaics

Background:

• Wide-band gap perovskites exhibit a large open-circuit voltage (Voc) deficit, limiting the efficiency of perovskite-based tandem solar cells.
• Surface defects and improper energy level alignment are key factors contributing to this Voc deficit.

Purpose of the Study:

• To develop and evaluate a two-step surface passivation (TSP) strategy to enhance the Voc of wide-band gap perovskite devices.
• To improve the overall performance and stability of perovskite solar cells.

Main Methods:

• A two-step surface passivation (TSP) strategy was employed, involving poly(2-ethyl-2-oxazoline) treatment and phenethylammonium salt layer deposition.
• The strategy focused on impurity removal, defect passivation, and energy level alignment optimization at the perovskite/hole transport layer interface.

Main Results:

• The TSP strategy effectively suppressed non-radiative recombination, leading to an average Voc increase of 60 mV.
• The champion 1.68 eV band gap device achieved a power conversion efficiency (PCE) of 21.8% with a Voc of 1.25 V.
• TSP-treated devices retained 86.3% of their initial PCE after 1032 hours of ambient aging, compared to 72.4% for control devices.

Conclusions:

• The proposed TSP strategy is highly effective in enhancing the Voc and stability of wide-band gap perovskite solar cells.
• This approach offers a promising pathway for advancing the performance of perovskite-based tandem solar cells.