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Molecular Aggregation of Naphthalene Diimide(NDI) Derivatives in Electron Transport Layers of Inverted Perovskite Solar Cells and Their Influence on the Device Performance
Author(s) -
Liu Wenbo,
Shaikh Dada B.,
Rao Pedada Srinivasa,
Bhosale Rajesh S.,
Said Ahmed Ali,
Mak Adrian M.,
Wang Zongrui,
Zhao Mu,
Gao Weibo,
Chen Bingbing,
Lam Yeng Ming,
Fan Weijun,
Bhosale Sidhanath V.,
Bhosale Sheshanath V.,
Zhang Qichun
Publication year - 2020
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.201901452
Subject(s) - perovskite (structure) , photoluminescence , cathode , materials science , electron mobility , chemical physics , spectroscopy , molecule , electron transport chain , absorption spectroscopy , absorption (acoustics) , chemistry , optoelectronics , crystallography , optics , composite material , organic chemistry , physics , biochemistry , quantum mechanics
One of key factors to design applicable electron transport layers (ETLs) for perovskite solar cells is the morphology of ETLs since a good morphology would help to facilitate the carrier transport at two interfaces (perovskite\ETL and ETL\cathode). However, one drawback of most organic ETL small molecules is the internal undesired accumulation, which would cause the formation of inappropriate morphology and rough ETL surface. Here, by elaborately designing the side chains of NDI derivatives, the molecular interaction could be modified to achieve the aggregation in different degrees, which would eventually affect the accumulation of molecules and surface qualities of ETLs. By speculating from the comparison between the absorption spectra of solutions and films, the sequence of extent of molecule interaction and aggregation was built among three NDI derivatives, which is further confirmed by direct evidence of atomic force microscopy (AFM) images. Then, carrier exaction abilities are simply studied by steady‐state photoluminescence spectroscopy. The carrier transport process is also discussed based on cyclic voltammetry, time‐resolved photoluminescence spectroscopy and mobility. NDIF1 are proven to have the appropriate internal aggregation to smooth the contact with cathode and low series resistance, and a device performance of 15.6 % is achieved. With the ability of preventing the thermal diffusion of Ag towards the perovskite surface due to the strong interaction between molecules, NDIF2 at high concentration shows the highest fill factor (80 %).