Elucidating the Impact of Molecular Packing and Device Architecture on the Performance of Nanostructured Perylene Diimide Solar Cells

Aluicio‐Sarduy, Eduardo; Singh, Ranbir; Kan, Zhipeng; Ye, Tengling; Baidak, Aliaksandr; Calloni, Alberto; Berti, Giulia; Duó, Lamberto; Iosifidis, Agathaggelos; Beaupré, Serge; Leclerc, Mario; Butt, Hans‐Jürgen; Floudas, George; Keivanidis, Panagiotis E.

doi:10.1021/acsami.5b00827

Cited by 25 publications

(36 citation statements)

References 52 publications

(120 reference statements)

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“…Excimer states have been observed in other NFAs [ 37,64,66 ] and act as low‐energy trap states that inhibit charge separation of bound electron–hole pairs at the donor–acceptor interface, reducing mobilities and PCEs. [ 36,67–70 ]…”

Section: Resultsmentioning

confidence: 99%

“…Excimer states have been observed in other NFAs [37,64,66] and act as lowenergy trap states that inhibit charge separation of bound electron-hole pairs at the donor-acceptor interface, reducing mobilities and PCEs. [36,[67][68][69][70] Comparing the normalized steadystate blend absorptions to the transient spectra at ≈1 ps at 580 nm reveals a signifi cant (≈40% and ≈50%) yield of free carriers from ultrafast hole transfer in ITzNF4 and ITNF4, respectively (Figure 7A,B). Monitoring the kinetics of 1* A reveals that ≈80% of 1* A decays within ≈500 fs in both the blends and neat acceptors (Figure 7C,D).…”

Section: Femtosecond Transient Absorption Spectroscopymentioning

confidence: 99%

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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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Section: Resultsmentioning

confidence: 99%

Section: Femtosecond Transient Absorption 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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“…77 Further investigations on the local structural order and molecular packing indicated that electronic connectivity between the large domains of PDI 1 reduced the electron mobility and the local disorder of the PDI domains was essential for efficient electron transport. 78,79 From transient absorption pump-probe spectroscopy, Laquai and coworkers illustrated that the charge separation between PDI 1 and PBDTTT-C is strongly eld-dependent. Upon excitation, both the PDI and polymer excitons undergo fast charge transfer on a time scale of several tens of picoseconds.…”

Section: Small-molecule Non-fullerene Acceptorsmentioning

confidence: 99%

New advances in non-fullerene acceptor based organic solar cells

2015

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“…S3). Since conventional OPV device geometries with bottom PEDOT:PSS hole-collecting electrodes consistently underestimate the performance of PDI-based OPV bulk heterojunctions,41 we have additionally studied the photovoltaic performance of inverted OPV devices with the glass/ITO/ZnO/PIF8BT:PDI/V2O5/Ag device configuration. Following thermal annealing, these devices performed better with an improvement in the order of ~ 40% for Jsc and of ~ 15% for Voc.Further characterization of the inverted OPV PIF8BT:PDI devices was carried out under variable photoexcitation intensity (Iexc) of continuous-wave (cw) laser light at 532 nm.…”

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confidence: 99%

Afterglow Effects as a Tool to Screen Emissive Nongeminate Charge Recombination Processes in Organic Photovoltaic Composites

Keivanidis

Itskos

Kan

et al. 2019

ACS Appl. Mater. Interfaces

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Disentangling temporally-overlapping charge carrier recombination events in organic bulk heterojunctions by optical spectroscopy is challenging. Here, a new methodology for employing delayed luminescence spectroscopy is presented. The proposed method is capable of distinguishing between recombination of spatially-separated charge carriers and trap-assisted charge recombination simply by monitoring the delayed luminescence (afterglow) of bulk heterojunctions with a quasi timeintegrated detection scheme. Applied on the model composite of the donor poly (6,12-dihydro-6,6,12,12-tetraoctyl-indeno[1,2-b]fluorene-alt-benzothiadiazole) (PIF8BT) polymer and the acceptor ethyl-propyl perylene diimide (PDI) derivative, i.e. PIF8BT:PDI, the luminescence of charge-transfer (CT) states created by non-geminate charge recombination on the ns -μs time scale is observed. Fluence-dependent, quasi time-integrated detection of the CT luminescence monitors exclusively emissive charge recombination events, while rejecting the contribution of other early-time emissive processes. Trap-assisted and bimolecular charge recombination channels are identified based on their distinct dependence on fluence. The importance of the two recombination channels is correlated with the layer's order and electrical properties of the corresponding devices. Four different microstructures of the PIF8BT:PDI composite obtained by thermal annealing are investigated. Thermal annealing of PIF8BT:PDI shrinks the PDI domains in parallel with the growth of the PIF8BT domains in the blend. Common to all states studied, the delayed CT luminescence signal is dominated by trap-assisted recombination. Yet, the minor fraction of fully-separated charge recombination in the overall CT emission increases as the difference in the size of the donor and acceptor domains in the PIF8BT:PDI blend becomes larger. Electric field-induced quenching measurements on complete PIF8BT:PDI devices confirm quantitatively the dominance of emissive trap-limited charge recombination and demonstrate that only 40% of the PIF8BT/PDI CT luminescence comes from the recombination of fully-separated charges, taking place within 200 ns after photoexcitation. The method is applicable to other non-fullerene acceptor blends beyond the system discussed here, if their CT state luminescence can be monitored.

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Elucidating the Impact of Molecular Packing and Device Architecture on the Performance of Nanostructured Perylene Diimide Solar Cells

Abstract: PSS electrode, thus impeding the efficient charge extraction and limiting device photocurrent.

Cited by 25 publications

References 52 publications

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

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

New advances in non-fullerene acceptor based organic solar cells

Afterglow Effects as a Tool to Screen Emissive Nongeminate Charge Recombination Processes in Organic Photovoltaic Composites

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