Correlated In Situ Low‐Frequency Noise and Impedance Spectroscopy Reveal Recombination Dynamics in Organic Solar Cells Using Fullerene and Non‐Fullerene Acceptors

Luck, Kyle A.; Sangwan, Vinod K.; Hartnett, Patrick E.; Arnold, Heather N.; Wasielewski, Michael R.; Marks, Tobin J.; Hersam, Mark C.

doi:10.1002/adfm.201703805

Cited by 27 publications

(19 citation statements)

References 128 publications

(296 reference statements)

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“…Furthermore, impedance spectroscopy (IS) under illumination was used to study charge transport in solar cells using both spin‐coated and printed polymer blends. IS has been widely applied to organic photovoltaics based on fullerene [ 39–41 ] and NFA [ 42 ] small molecules. We compare optimized PM6:ITIC‐4F devices using the two deposition methods, SC and IJP.…”

Section: Performance Of Nfa‐based Solar Cells Inkjet Printed From Nonmentioning

confidence: 99%

High‐Efficiency Digital Inkjet‐Printed Non‐Fullerene Polymer Blends Using Non‐Halogenated Solvents

Perkhun

Köntges

Pourcin³

et al. 2021

Adv Energy and Sustain Res

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Inkjet printing (IJP) of polymer solar cells is ideal for small‐area off‐grid electronics with low power consumption. However, IJP is quite a complex technique compared with techniques such as spin coating or doctor blading. The IJP of polymer blends is reported based on ITIC derivatives as non‐fullerene acceptors (NFAs) using non‐halogenated solvents. The results show that fluorination of NFA is essential to form highly stable inks in o‐xylene, because ITIC has significantly insufficient solubility compared with ITIC‐4F. The importance of tetralin as a multifunctional co‐solvent for printing highly efficient PM6:ITIC‐4F blends is demonstrated, as even at very low concentrations, tetralin not only improves ink jettability and open nozzle time, but also improves drying behavior of the blend layer, resulting in blends with homogeneous micro‐ and nanoscale morphology. The resulting solar cells using inkjet‐printed polymer blends show a maximum efficiency of 10.1%. Moreover, IJP produces significant changes in the nanoscale and microscale morphology. In particular, the formation of a thin PM6 capping layer on the blend surface along with improved phase separation and crystallinity in both the donor and acceptor greatly reduces the recombination of charge carriers in thick blends, making inkjet‐printed photoactive films very promising for industrial applications.

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Section: Performance Of Nfa‐based Solar Cells Inkjet Printed From Nonmentioning

confidence: 99%

High‐Efficiency Digital Inkjet‐Printed Non‐Fullerene Polymer Blends Using Non‐Halogenated Solvents

Perkhun

Köntges

Pourcin³

et al. 2021

Adv Energy and Sustain Res

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“…[79,80] Impedance spectroscopy has been used extensively to cor relate OSC performance with microstructures, interfaces, device architecture, and processing conditions. [81,82] Such noninvasive characterization is particularly wellsuited for BHJ devices with interpenetrating blend microstructures. In contrast to other transient measurement methods, such as photoCELIV, [83] impedance spectroscopy can be performed at open circuit voltage, interrogating the most relevant recombi nation processes in situ.…”

Section: Light Intensity Dependence and Impedance Spectroscopymentioning

confidence: 99%

“…The additional components, R 1 and C 1 , were needed to fit the highfrequency response, as simpler models of just R S , R rec , and C μ yield poor fits. [81,82,[84][85][86] The lowfrequency response represented by R rec and C μ captures the recombina tion dynamics. Nonideality of the heterogenous blend interfaces requires constant phase element (CPE) with magnitude Q such that, C μ = (R rec •Q) 1/n /R rec = τ avg /R rec where τ avg is the average of the distribution of lifetimes and n is the ideality factor.…”

Section: Light Intensity Dependence and Impedance Spectroscopymentioning

confidence: 99%

Fluorinating π‐Extended Molecular Acceptors Yields Highly Connected Crystal Structures and Low Reorganization Energies for Efficient Solar Cells

Swick

Alzola

Sangwan

et al. 2020

Advanced Energy Materials

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The synthesis and characterization of new semiconducting materials is essential for developing high‐efficiency organic solar cells. Here, the synthesis, physiochemical properties, thin film morphology, and photovoltaic response of ITN‐F4 and ITzN‐F4, the first indacenodithienothiophene nonfullerene acceptors that combine π‐extension and fluorination, are reported. The neat acceptors and bulk‐heterojunction blend films with fluorinated donor polymer poly{[4,8‐bis[5‐(2‐ethylhexyl)‐4‐fluoro‐2‐thienyl]benzo[1,2‐b:4,5‐b′]‐dithiophene‐2,6‐diyl]‐alt‐[2,5‐thiophenediyl[5,7‐bis(2‐ethylhexyl)‐4,8‐dioxo‐4H,8H‐benzo[1,2‐c:4,5‐c′]dithiophene‐1,3‐diyl]]} (PBDB‐TF, also known as PM6) are investigated using a battery of techniques, including single crystal X‐ray diffraction, fs transient absorption spectroscopy (fsTA), photovoltaic response, space‐charge‐limited current transport, impedance spectroscopy, grazing incidence wide angle X‐ray scattering, and density functional theory level computation. ITN‐F4 and ITzN‐F4 are found to provide power conversion efficiencies greater and internal reorganization energies less than their non‐π‐extended and nonfluorinated counterparts when paired with PBDB‐TF. Additionally, ITN‐F4 and ITzN‐F4 exhibit favorable bulk‐heterojunction relevant single crystal packing architectures. fsTA reveals that both ITN‐F4 and ITzN‐F4 undergo ultrafast hole transfer (<300 fs) in films with PBDB‐TF, despite excimer state formation in both the neat and blend films. Taken together and in comparison to related structures, these results demonstrate that combined fluorination and π‐extension synergistically promote crystallographic π‐face‐to‐face packing, increase crystallinity, reduce internal reorganization energies, increase interplanar π–π electronic coupling, and increase power conversion efficiency.

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“…227 In organic semiconductor devices, 1/f noise is introduced by resistance fluctuation and intrinsically caused by either charge carrier fluctuation or mobility fluctuation. 226,231…”

Section: Responsivitymentioning

confidence: 99%

Narrowband organic photodetectors – towards miniaturized, spectroscopic sensing

et al. 2022

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Correlated In Situ Low‐Frequency Noise and Impedance Spectroscopy Reveal Recombination Dynamics in Organic Solar Cells Using Fullerene and Non‐Fullerene Acceptors

Cited by 27 publications

References 128 publications

High‐Efficiency Digital Inkjet‐Printed Non‐Fullerene Polymer Blends Using Non‐Halogenated Solvents

High‐Efficiency Digital Inkjet‐Printed Non‐Fullerene Polymer Blends Using Non‐Halogenated Solvents

Fluorinating π‐Extended Molecular Acceptors Yields Highly Connected Crystal Structures and Low Reorganization Energies for Efficient Solar Cells

Narrowband organic photodetectors – towards miniaturized, spectroscopic sensing

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