[Paper] Atomic Layer Deposition of CdS Quantum Dots for Solid-State Quantum Dot Sensitized Solar Cells




Atomic Layer Deposition of CdS Quantum Dots for Solid-State Quantum Dot Sensitized Solar Cells, Thomas P. Brennan, Pendar Ardalan, Han-Bo-Ram Lee, Jonathan R. Bakke, I-Kang Ding, Michael D. McGehee, Stacey F. Bent, Advanced Energy Materials, 2011


http://dx.doi.org/10.1002/aenm.201100363


Abstract


Functioning quantum dot (QD) sensitized solar cells have been fabricated using the vacuum deposition technique atomic layer deposition (ALD). Utilizing the incubation period of CdS growth by ALD on TiO 2 , we are able to grow QDs of adjustable size which act as sensitizers for solid-state QD- sensitized solar cells (ssQDSSC). The size of QDs, studied with transmission electron microscopy (TEM), varied with the number of ALD cycles from 1-10 nm. Photovoltaic devices with the QDs were fabricated and characterized using a ssQDSSC device architecture with 2,2’,7,7’-tetrakis-(N,N-di-p meth- oxyphenylamine) 9,9’-spirobifl uorene (spiro-OMeTAD) as the solid-state hole conductor. The ALD approach described here can be applied to fabrication of quantum-confi ned structures for a variety of applications, including solar electricity and solar fuels. Because ALD provides the ability to deposit many materials in very high aspect ratio substrates, this work introduces a strategy by which material and optical properties of QD sensitizers may be adjusted not only by the size of the particles but also in the future by the composition.