Imperial College London

ProfessorIainMcCulloch

Faculty of Natural SciencesDepartment of Chemistry

Chair in Polymer Materials
 
 
 
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Contact

 

+44 (0)20 7594 5669i.mcculloch

 
 
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Location

 

RCS 1 M229ChemistrySouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

371 results found

Baran D, Gasparini N, Wadsworth A, Tan CH, Wehbe N, Song X, Hamid Z, Zhang W, Neophytou M, Kirchartz T, Brabec CJ, Durrant JR, McCulloch Iet al., 2018, Robust nonfullerene solar cells approaching unity external quantum efficiency enabled by suppression of geminate recombination, NATURE COMMUNICATIONS, Vol: 9, ISSN: 2041-1723

JOURNAL ARTICLE

Cha H, Tan CH, Wu J, Dong Y, Zhang W, Chen H, Rajaram S, Narayan KS, McCulloch I, Durrant JRet al., 2018, An Analysis of the Factors Determining the Efficiency of Photocurrent Generation in Polymer:Nonfullerene Acceptor Solar Cells, Advanced Energy Materials, ISSN: 1614-6832

© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Herein, a meta-analysis of the device performance and transient spectroscopic results are undertaken for various donor:acceptor blends, employing three different donor polymers and seven different acceptors including nonfullerene acceptors (NFAs). From this analysis, it is found that the primary determinant of device external quantum efficiency (EQE) is the energy offset driving interfacial charge separation, ΔECS. For devices employing the donor polymer PffBT4T blended with NFA and fullerene acceptors, an energy offset ΔECS = 0.30 eV is required to achieve near unity charge separation, which increases for blends with PBDTTT-EFT and P3HT to 0.36 and ≈1.2 eV, respectively. For blends with PffBT4T and PBDTTT-EFT, a 100 meV decrease in the LUMO of the acceptor is observed to result in an approximately twofold increase in EQE. Steady state and transient optical data determine that this energy offset requirement is not associated with the need to overcome the polymer exciton binding energy and thereby drive exciton separation, with all blends studied showing efficient exciton separation. Rather, the increase in EQE with larger energy offset is shown to result from suppression of geminate recombination losses. These results are discussed in terms of their implications for the design of donor/NFA interfaces in organic solar cells, and strategies to achieve further advances in device performance.

JOURNAL ARTICLE

Cha H, Wheeler S, Holliday S, Dimitrov SD, Wadsworth A, Lee HH, Baran D, McCulloch I, Durrant JRet al., 2018, Influence of Blend Morphology and Energetics on Charge Separation and Recombination Dynamics in Organic Solar Cells Incorporating a Nonfullerene Acceptor, ADVANCED FUNCTIONAL MATERIALS, Vol: 28, ISSN: 1616-301X

JOURNAL ARTICLE

Chen H-Y, Nikolka M, Wadsworth A, Yue W, Onwubiko A, Xiao M, White AJP, Baran D, Sirringhaus H, McCulloch Iet al., 2018, A Thieno[2,3-b]pyridine-Flanked Diketopyrrolopyrrole Polymer as an n-Type Polymer Semiconductor for All-Polymer Solar Cells and Organic Field-Effect Transistors, MACROMOLECULES, Vol: 51, Pages: 71-79, ISSN: 0024-9297

JOURNAL ARTICLE

Du W, Ohayon D, Combe C, Mottier L, Maria IP, Ashraf RS, Fiumelli H, Inal S, McCulloch Iet al., 2018, Improving the Compatibility of Diketopyrrolopyrrole Semiconducting Polymers for Biological Interfacing by Lysine Attachment, CHEMISTRY OF MATERIALS, Vol: 30, Pages: 6164-6172, ISSN: 0897-4756

JOURNAL ARTICLE

Gasparini N, Gregori A, Salvador M, Biele M, Wadsworth A, Tedde S, Baran D, McCulloch I, Brabec CJet al., 2018, Visible and Near-Infrared Imaging with Nonfullerene-Based Photodetectors, ADVANCED MATERIALS TECHNOLOGIES, Vol: 3, ISSN: 2365-709X

JOURNAL ARTICLE

Gasparini N, Wadsworth A, Moser M, Baran D, McCulloch I, Brabec CJet al., 2018, The Physics of Small Molecule Acceptors for Efficient and Stable Bulk Heterojunction Solar Cells, ADVANCED ENERGY MATERIALS, Vol: 8, ISSN: 1614-6832

JOURNAL ARTICLE

Giovannitti A, Maria IP, Hanifi D, Donahue MJ, Bryant D, Barth KJ, Makdah BE, Savva A, Moia D, Zetek M, Barnes PRF, Reid OG, Inal S, Rumbles G, Malliaras GG, Nelson J, Rivnay J, McCulloch Iet al., 2018, The Role of the Side Chain on the Performance of N-type Conjugated Polymers in Aqueous Electrolytes, CHEMISTRY OF MATERIALS, Vol: 30, Pages: 2945-2953, ISSN: 0897-4756

JOURNAL ARTICLE

Giovannitti A, Thorley KJ, Nielsen CB, Li J, Donahue MJ, Malliaras GG, Rivnay J, McCulloch Iet al., 2018, Redox-Stability of Alkoxy-BDT Copolymers and their Use for Organic Bioelectronic Devices, ADVANCED FUNCTIONAL MATERIALS, Vol: 28, ISSN: 1616-301X

JOURNAL ARTICLE

Inal S, Rivnay J, Suiu A-O, Malliaras GG, McCulloch Iet al., 2018, Conjugated Polymers in Bioelectronics, ACCOUNTS OF CHEMICAL RESEARCH, Vol: 51, Pages: 1368-1376, ISSN: 0001-4842

JOURNAL ARTICLE

Kiefer D, Giovannitti A, Sun H, Biskup T, Hofmann A, Koopmans M, Cendra C, Weber S, Anton Koster LJ, Olsson E, Rivnay J, Fabiano S, McCulloch I, Müller Cet al., 2018, Enhanced n-Doping Efficiency of a Naphthalenediimide-Based Copolymer through Polar Side Chains for Organic Thermoelectrics., ACS Energy Lett, Vol: 3, Pages: 278-285, ISSN: 2380-8195

N-doping of conjugated polymers either requires a high dopant fraction or yields a low electrical conductivity because of their poor compatibility with molecular dopants. We explore n-doping of the polar naphthalenediimide-bithiophene copolymer p(gNDI-gT2) that carries oligoethylene glycol-based side chains and show that the polymer displays superior miscibility with the benzimidazole-dimethylbenzenamine-based n-dopant N-DMBI. The good compatibility of p(gNDI-gT2) and N-DMBI results in a relatively high doping efficiency of 13% for n-dopants, which leads to a high electrical conductivity of more than 10-1 S cm-1 for a dopant concentration of only 10 mol % when measured in an inert atmosphere. We find that the doped polymer is able to maintain its electrical conductivity for about 20 min when exposed to air and recovers rapidly when returned to a nitrogen atmosphere. Overall, solution coprocessing of p(gNDI-gT2) and N-DMBI results in a larger thermoelectric power factor of up to 0.4 μW K-2 m-1 compared to other NDI-based polymers.

JOURNAL ARTICLE

Kiefer D, Giovannitti A, Sun H, Biskup T, Hofmann A, Koopmans M, Cendra C, Weber S, Koster LJA, Olsson E, Rivnay J, Fabiano S, McCulloch I, Muller Cet al., 2018, Enhanced n-Doping Efficiency of a Naphthalenediimide-Based Copolymer through Polar Side Chains for Organic Thermoelectrics, ACS ENERGY LETTERS, Vol: 3, Pages: 278-285, ISSN: 2380-8195

JOURNAL ARTICLE

Kosco J, Sachs M, Godin R, Kirkus M, Francas L, Bidwell M, Qureshi M, Anjum D, Durrant JR, McCulloch Iet al., 2018, The Effect of Residual Palladium Catalyst Contamination on the Photocatalytic Hydrogen Evolution Activity of Conjugated Polymers, Advanced Energy Materials, ISSN: 1614-6832

© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim The effect of residual Pd on hydrogen evolution activity in conjugated polymer photocatalytic systems is systematically investigated using colloidal poly(9,9-dioctylfluorene-alt-benzothiadiazole) (F8BT) nanoparticles as a model system. Residual Pd, originating from the synthesis of F8BT via Pd catalyzed polycondensation polymerization, is observed in the form of homogeneously distributed Pd nanoparticles within the polymer. Residual Pd is essential for any hydrogen evolution to be observed from this polymer, and very low Pd concentrations (<40 ppm) are sufficient to have a significant effect on the hydrogen evolution reaction (HER) rate. The HER rate increases linearly with increasing Pd concentration from <1 ppm to approximately 100 ppm, at which point the rate begins to saturate. Transient absorption spectroscopy experiments support these conclusions, and suggest that residual Pd mediates electron transfer from the F8BT nanoparticles to protons in the aqueous medium.

JOURNAL ARTICLE

Li N, McCulloch I, Brabec CJ, 2018, Analyzing the efficiency, stability and cost potential for fullerene-free organic photovoltaics in one figure of merit, ENERGY & ENVIRONMENTAL SCIENCE, Vol: 11, Pages: 1355-1361, ISSN: 1754-5692

JOURNAL ARTICLE

Liang R-Z, Babics M, Savikhin V, Zhang W, Le Corre VM, Lopatin S, Kan Z, Firdaus Y, Liu S, McCulloch I, Toney MF, Beaujuge PMet al., 2018, Carrier Transport and Recombination in Efficient "All-Small-Molecule" Solar Cells with the Nonfullerene Acceptor IDTBR, ADVANCED ENERGY MATERIALS, Vol: 8, ISSN: 1614-6832

JOURNAL ARTICLE

Liao H, Xiao C, Ravva MK, Wang Y, Little M, Jenart MVC, Onwubiko A, Li Z, Wang Z, Bredas J-L, McCulloch I, Yue Wet al., 2018, Synthesis and properties of isoindigo and benzo[1,2-b:4,5-b ']bis[b]benzothiophene oligomers, CHEMICAL COMMUNICATIONS, Vol: 54, Pages: 11152-11155, ISSN: 1359-7345

JOURNAL ARTICLE

Neophytou M, Bryant D, Lopatin S, Chen H, Hallani RK, Cater L, McCulloch I, Yue Wet al., 2018, Alternative Thieno[3,2-b][1]benzothiophene Isoindigo Polymers for Solar Cell Applications, MACROMOLECULAR RAPID COMMUNICATIONS, Vol: 39, ISSN: 1022-1336

JOURNAL ARTICLE

Nikolka M, Hurhangee M, Sadhanala A, Chen H, McCulloch I, Sirringhaus Het al., 2018, Correlation of Disorder and Charge Transport in a Range of Indacenodithiophene-Based Semiconducting Polymers, ADVANCED ELECTRONIC MATERIALS, Vol: 4, ISSN: 2199-160X

JOURNAL ARTICLE

Nikolka M, Schweicher G, Armitage J, Nasrallah I, Jellett C, Guo Z, Hurhangee M, Sadhanala A, McCulloch I, Nielsen CB, Sirringhaus Het al., 2018, Performance Improvements in Conjugated Polymer Devices by Removal of Water-Induced Traps, ADVANCED MATERIALS, Vol: 30, ISSN: 0935-9648

JOURNAL ARTICLE

Onwubiko A, Yue W, Jellett C, Xiao M, Chen H-Y, Ravva MK, Hanifi DA, Knall A-C, Purushothaman B, Nikolka M, Flores J-C, Salleo A, Bredas J-L, Sirringhaus H, Hayoz P, McCulloch Iet al., 2018, Fused electron deficient semiconducting polymers for air stable electron transport, NATURE COMMUNICATIONS, Vol: 9, ISSN: 2041-1723

JOURNAL ARTICLE

Pappa AM, Ohayon D, Giovannitti A, Maria LP, Savva A, Uguz I, Rivnay J, McCulloch L, Owens RM, Inal Set al., 2018, Direct metabolite detection with an n-type accumulation mode organic electrochemical transistor, SCIENCE ADVANCES, Vol: 4, ISSN: 2375-2548

JOURNAL ARTICLE

Paterson AF, Singh S, Fallon KJ, Hodsden T, Han Y, Schroeder BC, Bronstein H, Heeney M, McCulloch I, Anthopoulos TDet al., 2018, Recent Progress in High-Mobility Organic Transistors: A Reality Check, ADVANCED MATERIALS, Vol: 30, ISSN: 0935-9648

JOURNAL ARTICLE

Song X, Gasparini N, Nahid MM, Chen H, Macphee SM, Zhang W, Norman V, Zhu C, Bryant D, Ade H, McCulloch I, Baran Det al., 2018, A Highly Crystalline Fused-Ring n-Type Small Molecule for Non-Fullerene Acceptor Based Organic Solar Cells and Field-Effect Transistors, ADVANCED FUNCTIONAL MATERIALS, Vol: 28, ISSN: 1616-301X

JOURNAL ARTICLE

Strohm S, Machui F, Langner S, Kubis P, Gasparini N, Salvador M, McCulloch I, Egelhaaf H-J, Brabec CJet al., 2018, P3HT: non-fullerene acceptor based large area, semi-transparent PV modules with power conversion efficiencies of 5%, processed by industrially scalable methods, ENERGY & ENVIRONMENTAL SCIENCE, Vol: 11, Pages: 2225-2234, ISSN: 1754-5692

JOURNAL ARTICLE

Tan C-H, Gorman J, Wadsworth A, Holliday S, Subramaniyan S, Jenekhe SA, Baran D, McCulloch I, Durrant JRet al., 2018, Barbiturate end-capped non-fullerene acceptors for organic solar cells: tuning acceptor energetics to suppress geminate recombination losses, CHEMICAL COMMUNICATIONS, Vol: 54, Pages: 2966-2969, ISSN: 1359-7345

JOURNAL ARTICLE

Venkatraman V, Friedlein JT, Giovannitti A, Maria IP, McCulloch I, McLeod RR, Rivnay Jet al., 2018, Subthreshold Operation of Organic Electrochemical Transistors for Biosignal Amplification, ADVANCED SCIENCE, Vol: 5, ISSN: 2198-3844

JOURNAL ARTICLE

Wadsworth A, Baran D, Gorman J, McCulloch Iet al., 2018, CHAPTER 3: High-performance Organic Photovoltaic Donor Polymers, RSC Nanoscience and Nanotechnology, Pages: 69-108

© The Royal Society of Chemistry 2018. The field of organic photovoltaics has advanced a great deal over the last decade, with device efficiencies now exceeding 11%. A large part of this success can be attributed to the development of donor polymer materials, from their humble beginnings as homopolymers to the highly tuned push-pull copolymer and terpolymer materials that are now being reported on a regular basis. Through the careful use of chemical modification, it has been possible to design and synthesize a wide variety of donor polymers, allowing optimization of both the optoelectronic and structural properties of the materials. In doing so, more favourable active layer blends have been achieved and therefore significant improvements in device performance have been observed. Herein we discuss how the chemical design of donor polymers for organic photovoltaics has led to the emergence of high-performance materials.

BOOK CHAPTER

Wadsworth A, Hamid Z, Bidwell M, Ashraf RS, Khan JI, Anjum DH, Cendra C, Yan J, Rezasoltani E, Guilbert AAY, Azzouzi M, Gasparini N, Bannock JH, Baran D, Wu H, de Mello JC, Brabec CJ, Salleo A, Nelson J, Laquai F, McCulloch Iet al., 2018, Progress in Poly (3-Hexylthiophene) Organic Solar Cells and the Influence of Its Molecular Weight on Device Performance, ADVANCED ENERGY MATERIALS, Vol: 8, ISSN: 1614-6832

JOURNAL ARTICLE

Wadsworth A, Moser M, Marks A, Little MS, Gasparini N, Brabec CJ, Baran D, McCulloch Iet al., 2018, Critical review of the molecular design progress in non-fullerene electron acceptors towards commercially viable organic solar cells., Chem Soc Rev

Fullerenes have formed an integral part of high performance organic solar cells over the last 20 years, however their inherent limitations in terms of synthetic flexibility, cost and stability have acted as a motivation to develop replacements; the so-called non-fullerene electron acceptors. A rapid evolution of such materials has taken place over the last few years, yielding a number of promising candidates that can exceed the device performance of fullerenes and provide opportunities to improve upon the stability and processability of organic solar cells. In this review we explore the structure-property relationships of a library of non-fullerene acceptors, highlighting the important chemical modifications that have led to progress in the field and provide an outlook for future innovations in electron acceptors for use in organic photovoltaics.

JOURNAL ARTICLE

Zhang Y, Wustoni S, Savva A, Giovannitti A, McCulloch I, Inal Set al., 2018, Lipid bilayer formation on organic electronic materials, JOURNAL OF MATERIALS CHEMISTRY C, Vol: 6, Pages: 5218-5227, ISSN: 2050-7526

JOURNAL ARTICLE

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