Low-temperature solution-processed solar cells based on PbS colloidal quantum dot/CdS heterojunctions.

Chang, Liang-Yi; Lunt, Richard R; Brown, Patrick R; Bulović, Vladimir; Bawendi, Moungi G · Nano Lett · 2013

basic_science · Level V

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Abstract

PbS colloidal quantum dot heterojunction solar cells have shown significant improvements in performance, mostly based on devices that use high-temperature annealed transition metal oxides to create rectifying junctions with quantum dot thin films. Here, we demonstrate a solar cell based on the heterojunction formed between PbS colloidal quantum dot layers and CdS thin films that are deposited via a solution process at 80 °C. The resultant device, employing a 1,2-ethanedithiol ligand exchange scheme, exhibits an average power conversion efficiency of 3.5%. Through a combination of thickness-dependent current density-voltage characteristics, optical modeling, and capacitance measurements, the combined diffusion length and depletion width in the PbS quantum dot layer is found to be approximately 170 nm.