Premium
Impact of Conformality and Crystallinity for Ultrathin 4 nm Compact TiO 2 Layers in Perovskite Solar Cells
Author(s) -
Roelofs Katherine E.,
Pool Vanessa L.,
BobbSemple Dara A.,
Palmstrom Axel F.,
Santra Pralay K.,
Van Campen Douglas G.,
Toney Michael F.,
Bent Stacey F.
Publication year - 2016
Publication title -
advanced materials interfaces
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.671
H-Index - 65
ISSN - 2196-7350
DOI - 10.1002/admi.201600580
Subject(s) - materials science , crystallinity , thin film , annealing (glass) , nanotechnology , chemical engineering , atomic layer deposition , photovoltaics , mesoporous material , optoelectronics , perovskite (structure) , fabrication , dielectric spectroscopy , anti reflective coating , perovskite solar cell , layer (electronics) , photovoltaic system , composite material , electrode , electrochemistry , alternative medicine , ecology , chemistry , pathology , engineering , biology , biochemistry , catalysis , medicine
The rapid rise in power conversion efficiencies of lead‐based perovskite solar cells (PSCs) has established their promise, motivating scale‐up and commercialization. As a thin film solar cell, interfacial properties are key to the performance of PSCs; there is a need to further understand which properties are critical to control. In this work, the impact of the compact TiO 2 (com‐TiO 2 ) film properties on the performance of mesoporous PSCs is studied. Com‐TiO 2 layers are fabricated by spray pyrolysis as well as by atomic layer deposition (ALD), using ALD as a proof‐of‐concept method to achieve highly conformal films of precisely controlled thickness. The com‐TiO 2 layers' conformality and surface roughness are examined by microscopy techniques; their relative crystallinity is studied by grazing‐incidence X‐ray diffraction with a synchrotron source and an in situ annealing chamber; and completed devices are analyzed by J–V and impedance spectroscopy techniques. The results show that an ultraconformal com‐TiO 2 layer can be thinned to 4 nm and match the performance of a ≈50 nm spray‐pyrolysis TiO 2 layer. This work concludes that film conformality is the primary consideration for creating a high‐performing com‐TiO 2 layer, overriding any effects of film crystallinity—a finding that can guide fabrication choices for the scale‐up of PSCs.