Improved Photovoltaic Performance of CsPbI<SUB>3</SUB> Perovskite Colloidal Quantum Dots via Surface Ligand Management
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We demonstrate CsPbI3 perovskite colloidal quantum dot (CQD) solar cells with improved photovoltaic performance via developing the surface ligand management. CsPbI3 CQDs are composed of long-hydrocarbon and insulating surface ligands, leading to poor charge transport in solar cells. In a previous report, the surface ligands of CsPbI3 CQDs are replaced with short-chain acetate ions resulting from only hydrolysis of methyl acetate under controlled humidity. We employ acetate-based ionic salts dissolved in methyl acetate in order for more efficient ligand exchange of CsPbI3 CQDs, leading to enhanced electro-coupling and solar cell performance. Among the acetate-based ionic salts, sodium acetate showed the most efficient removal of original surface ligands without the fusion of CsPbI3 CQDs. The CsPbI3 CQD solar cells based on the sodium acetate-based ligand exchange showed the improved power conversion efficiency up to 12.4%, compared to the previously-reported device (10.7%).