In:
Advanced Energy Materials, Wiley, Vol. 7, No. 22 ( 2017-11)
Abstract:
Bulk heterojunction (BHJ) morphologies are vital to the device performance of organic solar cells (OSCs), including phase separation in lateral and vertical directions. However, the morphology developed from the blend solution is not easily predicted and controlled, especially in the vertical direction, because the BHJ morphology is kinetically frozen during the rapid solvent evaporation process. Here, a simple approach to control BHJ morphologies with optimized phase distribution for small molecule:[6,6]‐phenyl‐C71‐butyric acid methyl ester (PC 71 BM) blends by enhancing the substrate temperature during the spin‐coating process. Three molecules with various fluorine atoms in the end acceptor units are selected. The relationship among molecular structures, substrate temperature effects on the morphology, and device performances are symmetrically investigated. Low temperature induces a multiple‐sublayer‐like architecture with significantly varied distributions of composition, morphology, and localized state energy, while high processing temperature induces more uniform film. The short‐circuit current, open‐circuit voltage, and fill factor of the devices are tuned with synergic improvement of efficiency toward over 10% and 11% for conventional and inverted devices. This work reveals the origination of vertical phase segregation, and provides a facile strategy to optimize the hierarchical phase separation for enhancing the performance of OSCs.
Type of Medium:
Online Resource
ISSN:
1614-6832
,
1614-6840
DOI:
10.1002/aenm.201701548
Language:
English
Publisher:
Wiley
Publication Date:
2017
detail.hit.zdb_id:
2594556-7
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