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Direct correlation of nanoscale morphology and device performance to study photocurrent generation in donor enriched phases of polymer solar cells

Direct correlation of nanoscale morphology and device performance to study photocurrent generation in donor enriched phases of polymer solar cells

Authors :
Uli Würfel
Martin Pfannmöller
Sadok Ben Dkhil
Yatzil Alejandra Avalos Quiroz
Riva Alkarsifi
Sara Bals
Elena Barulina
David Müller
Christine Videlot-Ackermann
Olivier Margeat
Stephan Thierry Dubas
Claudia Caddeo
Pavlo Perkhun
Alessandro Mattoni
Jörg Ackermann
Noriyuki Yoshimoto
Tomoyuki Koganezawa
Birger Zimmermann
Daiki Kuzuhara
Chieh Luo
Centre Interdisciplinaire de Nanoscience de Marseille (CINaM)
Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)
Fraunhofer Institute for Solar Energy Systems (Fraunhofer ISE)
Fraunhofer (Fraunhofer-Gesellschaft)
University of Antwerp (UA)
European Project: 713750,H2020,H2020-MSCA-COFUND-2015,DOC2AMU(2016)
Publica
ANR-17-CE05-0020,NFA-15,Cellules solaires organiques à base d'accepteur non fullerène avec un rendement de 15% et une durée de vie de 10 ans(2017)
Source :
ACS Applied Materials & Interfaces, ACS Applied Materials & Interfaces, Washington, D.C. : American Chemical Society, 2020, ⟨10.1021/acsami.0c05884⟩, ACS Applied Materials & Interfaces, 2020, ⟨10.1021/acsami.0c05884⟩, ACS applied materials & interfaces, 12 (2020): 28404–28415. doi:10.1021/acsami.0c05884, info:cnr-pdr/source/autori:Ben Dkhil, Sadok; Perkhun, Pavlo; Luo, Chieh; Mueller, David; Alkarsifi, Riva; Barulina, Elena; Quiroz, Yatzil Alejandra Avalos; Margeat, Olivier; Dubas, Stephan Thierry; Koganezawa, Tomoyuki; Kuzuhara, Daiki; Yoshimoto, Noriyuki; Caddeo, Claudia; Mattoni, Alessandro; Zimmermann, Birger; Wuerfel, Uli; Pfannmoeller, Martin; Bals, Sara; Ackermann, Joerg; Videlot-Ackermann, Christine/titolo:Direct Correlation of Nanoscale Morphology and Device Performance to Study Photocurrent Generation in Donor-Enriched Phases of Polymer Solar Cells/doi:10.1021%2Facsami.0c05884/rivista:ACS applied materials & interfaces (Print)/anno:2020/pagina_da:28404/pagina_a:28415/intervallo_pagine:28404–28415/volume:12, ACS applied materials and interfaces
Publication Year :
2020

Abstract

The nanoscale morphology of polymer blends is a key parameter to reach high efficiency in bulk heterojunction solar cells. Thereby, research typically focusing on optimal blend morphologies while studying nonoptimized blends may give insight into blend designs that can prove more robust against morphology defects. Here, we focus on the direct correlation of morphology and device performance of thieno[3,4-b]-thiophene-alt-benzodithiophene (PTB7):[6,6]phenyl C-71 butyric acid methyl ester (PC71BM) bulk heterojunction (BHJ) blends processed without additives in different donor/acceptor weight ratios. We show that while blends of a 1:1.5 ratio are composed of large donor-enriched and fullerene domains beyond the exciton diffusion length, reducing the ratio below 1:0.5 leads to blends composed purely of polymer-enriched domains. Importantly, the photocurrent density in such blends can reach values between 45 and 60% of those reached for fully optimized blends using additives. We provide here direct visual evidence that fullerenes in the donor-enriched domains are not distributed homogeneously but fluctuate locally. To this end, we performed compositional nanoscale morphology analysis of the blend using spectroscopic imaging of low-energy-loss electrons using a transmission electron microscope. Charge transport measurement in combination with molecular dynamics simulations shows that the fullerene substructures inside the polymer phase generate efficient electron transport in the polymer-enriched phase. Furthermore, we show that the formation of densely packed regions of fullerene inside the polymer phase is driven by the PTB7:PC71BM enthalpy of mixing. The occurrence of such a nanoscale network of fullerene clusters leads to a reduction of electron trap states and thus efficient extraction of photocurrent inside the polymer domain. Suitable tuning of the polymer-acceptor interaction can thus introduce acceptor subnetworks in polymer-enriched phases, improving the tolerance for high-efficiency BHJ toward morphological defects such as donor-enriched domains exceeding the exciton diffusion length.

Details

ISSN :
19448244 and 19448252
Database :
OpenAIRE
Journal :
ACS Applied Materials & Interfaces
Accession number :
edsair.doi.dedup.....ce757bf5862243f0e4ba98b55e3a1b74
Full Text :
https://doi.org/10.1021/acsami.0c05884