One-Step Deposition of Photovoltaic Layers Using Iodide Terminated PbS Quantum Dots.
We present a one-step layer deposition procedure employing ammonium iodide (NH4I) to achieve photovoltaic quality PbS quantum dot (QD) layers. Ammonium iodide is used to replace the long alkyl organic native ligands binding to the QD surface resulting in iodide terminated QDs that are stabilized in polar solvents such as N,N-dimethylformamide without particle aggregation. We extensively characterized the iodide terminated PbS QD via UV-vis absorption, transmission electron microscopy (TEM), thermogravimetric analysis (TGA), FT-IR transmission spectroscopy, and X-ray photoelectron spectroscopy (XPS). Finally, we fabricated PbS QD photovoltaic cells that employ the iodide terminated PbS QDs. The resulting QD-PV devices achieved a best power conversion efficiency of 2.36% under ambient conditions that is limited by the layer thickness. The PV characteristics compare favorably to similar devices that were prepared using the standard layer-by-layer ethandithiol (EDT) treatment that had a similar layer thickness.
†Nanomechanical Systems Research Division, Korea institute of Machinery and Materials, Daejeon 305-343, Republic of Korea.|§National Renewable Energy Laboratory, Golden, Colorado 80401, United States.
Sungwoo
S
Kim
†Nanomechanical Systems Research Division, Korea institute of Machinery and Materials, Daejeon 305-343, Republic of Korea.
Jaehong
J
Noh
†Nanomechanical Systems Research Division, Korea institute of Machinery and Materials, Daejeon 305-343, Republic of Korea.|#Department of Nanomechatronics, University of Science and Technology, Daejeon 305-350, Republic of Korea.
Hyekyoung
H
Choi
†Nanomechanical Systems Research Division, Korea institute of Machinery and Materials, Daejeon 305-343, Republic of Korea.
Heonseok
H
Ha
†Nanomechanical Systems Research Division, Korea institute of Machinery and Materials, Daejeon 305-343, Republic of Korea.
Jung Hoon
JH
Song
†Nanomechanical Systems Research Division, Korea institute of Machinery and Materials, Daejeon 305-343, Republic of Korea.
Hyung Cheoul
HC
Shim
†Nanomechanical Systems Research Division, Korea institute of Machinery and Materials, Daejeon 305-343, Republic of Korea.
Jihoon
J
Jang
§National Renewable Energy Laboratory, Golden, Colorado 80401, United States.
Matthew C
MC
Beard
†Nanomechanical Systems Research Division, Korea institute of Machinery and Materials, Daejeon 305-343, Republic of Korea.|#Department of Nanomechatronics, University of Science and Technology, Daejeon 305-350, Republic of Korea.
Sohee
S
Jeong
Iodide; Quantum dot; layer-by-layer process; ligand exchange; one-step deposition process