Morphology and carrier non-geminate recombination dynamics regulated by solvent additive in polymer/fullerene solar cells

In this study, PBDTTT-E (based on benzo [1,2-b:4,5-b′] dithiophene (BDT) and thieno [3,4-b] thiophene (TT)) as a donor and fullerene derivative PC 71 BM (phenyl-C 71 -butyric acid methyl ester) as an acceptor with and without 1,8-diiodooctane (DIO)-treated copolymer solar cells were investigated. Th...

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Bibliographic Details
Published in:RSC advances 2020-06, Vol.1 (39), p.23128-23135
Main Authors: Huo, Ming-Ming, Hu, Rong, Zhang, Qing-Shan, Chen, Shaoting, Gao, Xing, Zhang, Yi, Yan, Wei, Wang, Yong
Format: Article
Language:English
Subjects:
Butyric acid
Carrier density
Carrier lifetime
Carrier recombination
Carrier transport
Charge density
Chemistry
Circuits
Copolymers
Current carriers
Electron mobility
Fullerenes
Morphology
Open circuit voltage
Photovoltaic cells
Solar cells
Transient photovoltage
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Summary:In this study, PBDTTT-E (based on benzo [1,2-b:4,5-b′] dithiophene (BDT) and thieno [3,4-b] thiophene (TT)) as a donor and fullerene derivative PC 71 BM (phenyl-C 71 -butyric acid methyl ester) as an acceptor with and without 1,8-diiodooctane (DIO)-treated copolymer solar cells were investigated. The device based on PBDTTT-E with treated DIO showed remarkably high current density ( J sc ), fill factor (FF) and similar open-circuit voltage ( V oc ). Charge carrier lifetime ( τ n ), density ( n ) and non-geminate recombination rate ( k rec ) in the photoactive layers were measured by employing transient photovoltage (TPV) and charge extraction (CE) techniques. Based on k rec and n , J - V curves were reconstructed. The DIO optimized the morphology of the active layer and its PBDTTT-E:PC 71 BM interfaces were increased. Therefore, compared to the device without the treated DIO, the device with the treated DIO showed larger electron mobility, longer carrier lifetime ( τ n ) and lower non-geminate recombination rate ( k rec ), which enhances the carrier transport and restrains the non-geminate recombination, realizing the higher J sc and FF. In addition, that the DIO-treated devices can weaken the role of other factors (such as field dependent geminate recombination) in limiting device performance. The results provide some hints of improved device performance upon DIO as an additive in the D-A type polymer/fullerene solar cells. The device (PBDTTT-E:PC 71 BM) with DIO treated show lower non-geminate combination rate ( k rec ) and non-geminate combination current ( J NGR ). This indicates that DIO treatment can restrain the non-geminate recombination, realizing the higher J sc and FF.
ISSN:2046-2069
2046-2069
DOI:10.1039/d0ra03389h