Atomic layer deposition in nanostructured photovoltaics: tuning optical, electronic and surface properties

Abstract

Nanostructured materials offer key advantages for third-generation photovoltaics, such as the ability to achieve high optical absorption together with enhanced charge carrier collection using low cost components. However, the extensive interfacial areas in nanostructured photovoltaic devices can cause high recombination rates and a high density of surface electronic states. In this feature article, we provide a brief review of some nanostructured photovoltaic technologies including dye-sensitized, quantum dot sensitized and colloidal quantum dot solar cells. We then introduce the technique of atomic layer deposition (ALD), which is a vapor phase deposition method using a sequence of self-limiting surface reaction steps to grow thin, uniform and conformal films. We discuss how ALD has established itself as a promising tool for addressing different aspects of nanostructured photovoltaics. Examples include the use of ALD to synthesize absorber materials for both quantum dot and plasmonic solar cells, to grow barrier layers for dye and quantum dot sensitized solar cells, and to infiltrate coatings into colloidal quantum dot solar cell to improve charge carrier mobilities as well as stability. We also provide an example of monolayer surface modification in which adsorbed ligand molecules on quantum dots are used to tune the band structure of colloidal quantum dot solar cells for improved charge collection. Finally, we comment on the present challenges and future outlook of the use of ALD for nanostructured photovoltaics.

Enhancing activity in a nanostructured BiVO4 photoanode with a coating of microporous Al2O3

“…A summary of the two effects, at low bias and at higher bias is shown schematically in Figure 7E. Effects of Al2O3 such as lowering recombination rates and enhancing charge carrier mobility have been suggested and reviewed recently for barrier coatings on other types of semiconductors [54].…”

“…More recently, also atomic layer deposition (ALD) methods have been suggested for Al2O3 barrier layer coatings [15,16,17]. Effects primarily on electron tunnel kinetics based on the more dense and less/non-porous ALD Al2O3 films have been discussed [18].…”

CsPbBr3 QD/AlOx Inorganic Nanocomposites with Exceptional Stability in Water, Light, and Heat

“…[30] Fourier transform infrared spectroscopy (FTIR) was utilized to investigate the fate of the ligands and the eventual intercalation of TMA in the ligand shell ( Figure 2C). [34] Then, the optical properties of the pristine QDs and the nanocomposites were compared ( Figure S11). [31] After the TMA pulse,t he main change in the spectrum is the appearance of two strong and sharp bands at 1591 cm À1 and 1496 cm À1 ,which are characteristic of the COO À stretching modes.T he FTIR spectrum of the nanocomposites shows as trong OH peak centered around 3450 cm À1 .Such asignal is expected for alumina grown by an ALD process at low temperature,w hich should contain many hydroxy impurities.…”

Nanoengineering Energy Conversion and Storage Devices via Atomic Layer Deposition

“…Finally, the challenges regarding the material synthesis and scalable manufacturing of the ALD technique are also discussed. [14][15][16][17][18][19][20] Here, we will focus on the application of ALD technique for energy conversion and storage devices starting with an introduction of two important features of ALD, including (i) high aspect ratio conformity and (ii) thickness, composition and Review wileyonlinelibrary.com crystalline controllability. [2][3][4][5][6] It is well recognized that, for the energy conversion and storage devices, nanomaterials could offer effective light absorption, favorable charge and ion transfer, as well as accommodation of volume changes associated with some chemical reactions and phase transitions.…”