Premium
Directed Vertical Diffusion of Photovoltaic Active Layer Components into Porous ZnO‐Based Cathode Buffer Layers
Author(s) -
Kang JiaJhen,
Yang TsungYu,
Lan YiKang,
Wu WeiRu,
Su ChunJen,
Weng ShihChang,
Yamada Norifumi L.,
Su AnChung,
Jeng USer
Publication year - 2018
Publication title -
small
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.785
H-Index - 236
eISSN - 1613-6829
pISSN - 1613-6810
DOI - 10.1002/smll.201704310
Subject(s) - active layer , cathode , materials science , fullerene , optoelectronics , porosity , layer (electronics) , diffusion , polymer solar cell , polymer , chemical engineering , nanotechnology , energy conversion efficiency , chemistry , composite material , organic chemistry , physics , engineering , thermodynamics , thin film transistor
Cathode buffer layers (CBLs) can effectively further the efficiency of polymer solar cells (PSCs), after optimization of the active layer. Hidden between the active layer and cathode of the inverted PSC device configuration is the critical yet often unattended vertical diffusion of the active layer components across CBL. Here, a novel methodology of contrast variation with neutron and anomalous X‐ray reflectivity to map the multicomponent depth compositions of inverted PSCs, covering from the active layer surface down to the bottom of the ZnO‐based CBL, is developed. Uniquely revealed for a high‐performance model PSC are the often overlooked porosity distributions of the ZnO‐based CBL and the differential diffusions of the polymer PTB7‐Th and fullerene derivative PC 71 BM of the active layer into the CBL. Interface modification of the ZnO‐based CBL with fullerene derivative PCBEOH for size‐selective nanochannels can selectively improve the diffusion of PC 71 BM more than that of the polymer. The deeper penetration of PC 71 BM establishes a gradient distribution of fullerene derivatives over the ZnO/PCBE‐OH CBL, resulting in markedly improved electron mobility and device efficiency of the inverted PSC. The result suggests a new CBL design concept of progressive matching of the conduction bands.