In-situ entropic ligand engineering enables high-efficiency quantum dot solar cells

Area of Science:

• Materials Science
• Nanotechnology
• Photovoltaics

Background:

• Metal halide perovskite quantum dots (PQDs), especially formamidinium lead triiodide (FAPbI3) PQDs, are promising for high-efficiency solar cells due to their optical properties and phase stability.
• Challenges remain in achieving optimal colloidal dispersion and charge transport for FAPbI3 PQDs.

Purpose of the Study:

• To develop an efficient in-situ entropic ligand engineering strategy for FAPbI3 PQDs.
• To improve the dispersibility, charge transport, and overall performance of FAPbI3 PQD-based solar cells.

Main Methods:

• An entropic ligand engineering strategy using bis(2-ethylhexyl) phosphate (DEHP) was employed.
• The DEHP ligand's branched tails and phosphinic acid head were utilized to enhance colloidal stability and surface passivation.
• Optimization of DEHP ligand concentration was performed.

Main Results:

• The DEHP ligand improved the dispersibility and colloidal stability of FAPbI3 PQDs.
• Enhanced surface passivation and reduced core-core interactions were observed.
• The optimized DEHP-capped PQD solar cells achieved a power conversion efficiency (PCE) of 18.68% (certified 18.23%) with improved stability.

Conclusions:

• The in-situ entropic ligand engineering strategy using DEHP is effective for improving FAPbI3 PQD solar cells.
• This approach offers insights for designing and synthesizing metal halide PQDs for optoelectronic applications.
• The study demonstrates a viable route to high-performance and stable perovskite quantum dot solar cells.