Themed collection Special issue in honour of Kees Hummelen
There is a hole in my bucky: perspective on a maverick
In this perspective Kees Hummelen's contributions to fullerene research in our group at Santa Barbara, as well as Kees’ enormous contributions to organic electronics, will be presented as a set of “vignettes”.
Introduction to the themed issue in honour of Prof. Kees Hummelen
Guest editors Hennie Valkenier, Dirk Vanderzande, Andries Meijerink and Maurizio Prato introduce this Journal of Materials Chemistry C issue in honour of Professor Kees Hummelen on the occasion of his retirement.
Electron and hole transport in solution-processed fullerenes
Methanofullerene [6,6]-phenyl C61-butyric acid methyl ester and its derivatives have been the workhorse acceptors in organic bulk heterojunction solar cells for more than two decades. Here, an overview of their charge transport properties is given.
Kees Hummelen: a creative, inspirational and unorthodox scientist from Groningen
The carbon–carbon triple bond as a tool to design organic semiconductors for photovoltaic applications: an assessment of prospects and challenges
This Perspective discusses the developments, opportunities, and challenges in the context of the use of alkyne-based organic semiconductors in photovoltaic devices.
Emerging electronic applications of fullerene derivatives: an era beyond OPV
This review highlights the important role of fullerene derivatives in several emerging research directions beyond OPV and summarizes recent progresses in the development of fullerene derivatives to boost device performance in these new fields.
Lanthanide-doped nanoparticles in photovoltaics – more than just upconversion
This review summarizes recent advances in developing high-efficiency upconversion nanoparticles and nanomaterials for photovoltaic application.
Metal–organic framework based systems for CO2 sensing
Monitoring CO2 levels in the atmosphere as well as in work place environments is strictly regulated.
Diketopyrrolopyrrole-based single molecules in photovoltaic technologies
Diketopyrrolopyrroles stand out due to their chemical and optoelectronic properties. Diketopyrrolopyrrole-single molecules applied in organic, dye-sensitized and perovskite solar cells are presented to give clues for future molecular optimizations.
Single-molecule conductance variations of up to four orders of magnitude via contacting electrodes with different anchoring sites
Control of conductance through a single molecule via alternating anchoring points provides a unique perspective to design single-molecule electronic devices.
Efficient wide-bandgap copolymer donors with reduced synthesis cost
Two wide-bandgap copolymer donors with reduced synthesis cost offered decent PCEs up to 15.25% in organic solar cells.
A method for identifying the cause of inefficient salt-doping in organic semiconductors
To assess if salt-doping leaves anions and cations in the film, limiting the conductivity, one can apply a bias voltage and monitor the conductivity over time. If the doping is limited by unwanted ions, then the conductivity will increase with time.
Facile synthesis of annulated benzothiadiazole derivatives and their application as medium band gap acceptors in organic photovoltaic devices
Two benzothiadiazole derivatives annulated with 2-(1,3-dithiol-2-ylidene)malonitrile in the 4,5-position were prepared by a one-step procedure, and investigated as end-groups in non-fullerene acceptors for indoor photovoltaic applications.
Understanding the dopant induced effects on SFX-MeOTAD for perovskite solar cells: a spectroscopic and computational investigation
First-time spectroscopic and computational investigations to elucidate the role of a dicationic salt in the optical, electrical and electronic properties of a triarylamine hole transport material, SFX-MeOTAD.
Coordination mechanism of cyanine dyes on the surface of core@active shell β-NaGdF4:Yb3+,Er3+ nanocrystals and its role in enhancing upconversion luminescence
The sensitization of lanthanide-doped upconversion nanocrystals (UCNCs) using organic dyes with a broad and intense optical absorption is an interesting approach for efficient excitation-energy harvesting and enhancing the upconversion luminescence.
The hole in the bucky: structure–property mapping of closed- vs. open-cage fullerene solar-cell blends via temperature/composition phase diagrams
Experimentally established, non-equilibrium temperature/composition phase diagrams are demonstrated to be useful beyond rationalization of optimum OPV blend composition but also as tools for rapid, qualitative structure–property mapping.
Subphthalocyanine-based electron-transport materials for perovskite solar cells
Here, we explore the potential of subphthalocyanines (SubPcs) as ETMs in PSCs, where the perovskite is deposited by either solution processing or thermal evaporation. A maximum PCE of 10.8% was achieved with the champion device.
Fullerene derivatives with oligoethylene–glycol side chains: an investigation on the origin of their outstanding transport properties
The synergistic use of X-ray scattering and molecular dynamics simulations reveals the structure–property relationships of fullerene derivatives with oligoethylene–glycol side chains.
Supramolecular organic–inorganic domains integrating fullerene-based acceptors with polyoxometalate-bis-pyrene tweezers for organic photovoltaic applications
Polyoxometalate-bis-pyrene receptors for phenyl-C61-butyric acid methyl ester (PCBM) provide an interfacial layer (IFL) material enhancing the open circuit voltage of the organic photovoltaic device of about 34% under applied bias of ±5 V.
Three-state molecular potentiometer based on a non-symmetrically positioned in-backbone linker
We report on the synthesis and single-molecule conductance of a para-oligo(phenylene)ethynylene derivative with a non-symmetric positioned internal anchor group that gives rise to three conduction pathways of well distinctive conductance and length.
Induced axial chirality by a tight belt: naphthalene chromophores fixed in a 2,5-substituted cofacial para-phenylene–ethynylene framework
We report the design of a synthetically easy accessible axial chirality-inducing framework for an achiral chromophore of choice. The spatial arrangement excitonically couples the chromophores and thus results in intense molar dichroism.
Unexpectedly flexible graphene nanoribbons with a polyacene ladder skeleton
A new aromatic ladder polymer with a polyacene skeleton shows an unexpectedly high flexibility of its double-stranded backbone.
New thiophene-based conjugated macrocycles for optoelectronic applications
Two thiophene-based macrocycles have been synthesised and their optoelectronics applications have been investigated.
A ternary organic solar cell with 15.6% efficiency containing a new DPP-based acceptor
A new non-fullerene small molecule (MPU6) containing thienylethynylselenophene bridges, has been studied as an acceptor along with PC71BM and TDTBTA as a donor in ternary solution-processed bulk heterojunction polymer solar cells, showing a PCE of 15.60%.
Combined healing and doping of transition metal dichalcogenides through molecular functionalization
Twofold effect of molecular functionalization of defective transition metal dichalcogenides (TMDCs).
Effects of alkyl side chains of double-cable conjugated polymers on the photovoltaic performance of single-component organic solar cells
The effects of alkyl side units in double-cable conjugated polymers on the photovoltaic performance of single-component organic solar cells were systematically studied.
About this collection
We are pleased to introduce you to this collection from Journal of Materials Chemistry C in honour of Prof. J.C. (Kees) Hummelen, on the occasion of his retirement.
In this collection we cover topics that have been at the core of the scientific activity of Prof. Hummelen. Kees as a chemist has had a tremendous impact in materials science, as he helped transform a beautiful molecule, the buckminsterfullerene, into a useful one. He was, in fact, the person who developed for the first time a fullerene derivative, named PCBM, which has been adopted in the field of organic photovoltaics for the last 25 years. Kees’ passion for renewable energy and the development of materials for solar cells went further as he developed many more molecules both for photovoltaics and for thermoelectric applications. In many instances, the new materials were based on fullerene derivatives.
As a curious and passionate scientist, Kees has had many collaborations with physicist and engineers, and with them he investigated several devices but most of all solar cells. He has never been afraid to adventure in new fields always at the interface of chemistry with energy. In the last few years, one of his interests has been the use of upconversion, as he pioneered hybrid nanostructures which could harvest low energy photons and convert them into higher energy ones. This same curiosity and passion of Kees also led him to study the relationship between molecular structure and the conductance through single molecules or monolayers.
We hope you enjoy reading this collection of papers in Journal of Materials Chemistry C in honour of Kees Hummelen.