Marina Freitag

Newcastle University | NCL · School of Chemistry

Redox mediators play a major role determining the photocurrent and the photovoltage in dye-sensitized solar cells (DSCs). To maintain the photocurrent, the reduction of oxidized dye by the redox mediator should be significantly faster than the back electron transfer between TiO2 and the oxidized dye. The driving force for dye regeneration with the...

Solar cells that operate efficiently under indoor lighting are of great practical interest as they can serve as electric power sources for portable electronics and devices for wireless sensor networks or the Internet of Things. Here, we demonstrate a dye-sensitized solar cell (DSC) that achieves very high power-conversion efficiencies (PCEs) under...

The field of photovoltaics gives the opportunity to make our buildings ‘‘smart’’ and our portable devices “independent”, provided effective energy sources can be developed for use in ambient indoor conditions. To address this important issue, ambient light photovoltaic cells were developed to power autonomous Internet of Things (IoT) devices, capab...

Dye-sensitized solar cells (DSCs) are celebrating their 30th birthday and they are attracting a wealth of research efforts aimed at unleashing their full potential. In recent years, DSCs and dye-sensitized photoelectrochemical cells (DSPECs) have experienced a renaissance as the best technology for several niche applications that take advantage of...

Conventional redox mediators based on metal coordination complexes undergo electron transfer through the change in oxidation state of the metal center. However, electron transfer kinetics are offset toward preferred oxidation states when preorganized ligands constrain the reorganization of the coordination sphere. In contrast, we report here on dim...

Ambient energy harvesting has great potential to contribute to sustainable development and address growing environmental challenges. Converting waste energy from energy-intensive processes and systems (e.g., combustion engines and furnaces) is crucial to reducing their environmental impact and achieving net-zero emissions. Compact energy harvesters...

Despite record-breaking devices, interfaces in perovskite solar cells are still poorly understood, inhibiting further progress. The mixed ionic-electronic nature of lead-halide perovskites results in compositional variations at the interfaces, depending on the history of externally applied biases. This makes it difficult to measure critical paramet...

In response to the current trend of miniaturization of electronic devices and sensors, the complementary coupling of high-efficiency energy conversion and low-loss energy storage technologies has given rise to the development of photocapacitors (PCs), which combine energy conversion and storage in a single device. Photovoltaic systems integrated wi...

As the number of Internet of Things devices is rapidly increasing, there is an urgent need for sustainable and efficient energy sources and management practices in ambient environments. In response, we developed a high-efficiency ambient photovoltaic based on sustainable non-toxic materials and present a full implementation of a long short-term mem...

Two coordination complexes have been made by combining the dithiolene complexes [M(mnt)2]2- (mnt = maleonitriledithiolate; M = Ni2+ or Cu2+) as anion, with the copper(II) coordination complex [Cu(Stetra)] (Stetra = 6,6'-bis(4,5-dihydrothiazol-2-yl)-2,2'-bipyri-dine) as cation. The variation of the metal centers leads to a dramatic change in the con...

As the number of Internet of Things devices is rapidly increasing, there is an urgent need for sustainable and efficient energy sources and management practices in ambient environments. In response, we developed a high-efficiency ambient photovoltaic based on sustainable non-toxic materials and present a full implementation of a long short-term mem...

The deployment of photovoltaic technologies is forecast to increase substantially in the near to mid future to meet society's energy demand in a sustainable way. Dye-sensitized solar cells (DSSCs) in...

Here we demonstrate a new concept in PV in which devices are designed to minimize variability in generation. Modelling of the UK energy network predicts that such devices yield greater reductions in carbon emissions than conventional PV technology.

In this work, we report the synthesis of a room-temperature-stable electride (RoSE) reagent, namely K⁺(LiHMDS)e⁻ (1) (HMDS: 1,1,1,3,3,3-hexamethyldisilazide), from accessible starting materials (potassium metal and LiHMDS) via mechanochemical ball milling at 20 mmol scale. Despite its amorphous nature, the presence of anionic electrons in 1, key di...

Dye-sensitized solar cells are promising candidates for low-cost indoor power generation applications. However, they currently suffer from complex fabrication and stability issues arising from the liquid electrolyte. Consequently, the so-called zombie cell was developed, in which the liquid electrolyte is dried out to yield a solid through a pinhol...

Conductive coordination polymers are hybrid materials with the potential to be implemented in the next generation of electronic devices, owing to several desirable properties. A decade ago, only a few scattered examples exhibiting conductivity existed within this class of materials, yet today groups of coordination polymers possess electrical condu...

Emerging technologies in solar energy will be critical in enabling worldwide society in overcoming the present energy challenges and reaching carbon net zero. Inefficient and unstable charge transport materials limit...

A new generation of octahedral iron(II)-N-heterocyclic carbene (NHC) complexes, employing different tridentate C^N^C ligands, has been designed and synthesized as earth-abundant photosensitizers for dye sensitized solar cells (DSSCs) and related...

The impending implementation of billions of Internet of Things and wireless sensor network devices has the potential to be the next digital revolution, if energy consumption and sustainability constraints can be overcome. Ambient photovoltaics provide vast universal energy that can be used to realise near-perpetual intelligent IoT devices which can...

The present perspective presents a number of issues related to the current direction of DSSC research, with emphasis on the transition from iodide-containing electrolyte to charge-transport medium (CTM), electrolytes or solid-state conductors based on inorganic coordination complexes, aiming to attain a better light-to-electricity conversion effici...

The present perspective presents a number of issues related to the current direction of DSSC research, with emphasis on the transition from iodide-containing electrolyte to charge-transport medium (CTM), electrolytes or solid-state conductors based on inorganic coordination complexes, aiming to attain a better light-to-electricity conversion effici...

Indenofluorene‐extended tetrathiafulvalenes (IF‐TTFs) comprise a class of π‐conjugated sensitizers that exhibit strong absorptions in the visible region and two reversible one‐electron oxidations. Herein we present the synthesis and optical as well as redox properties of novel IF‐TTF donor‐acceptor scaffolds that were integrated in dye‐sensitized s...

Copper coordination complexes have emerged as a group of transition metal complexes that play important roles in solar energy conversion, utilization and storage, and have the potential to replace the quintessential commonly used transition metals, like Co, Pt, Ir and Ru as light sensitizers, redox mediators, electron donors and catalytic centers....

In this work, high performance four-terminal solution-processed tandem solar cells were fabricated by using dye-sensitized solar cells (DSSC) as top-cells and lead sulfide (PbS) colloidal quantum dot solar cells (CQDSC) as bottom-cells. For dye-sensitized top-cells, three different dye combinations were used while the titanium dioxide (TiO2) scatte...

Copper redox mediators can be employed in dye sensitized solar cells (DSCs) both as liquid electrolyte or as solid state hole transport materials (HTMs). The solid state devices, employing copper complex HTMs can be simply obtained by solvent evaporation in liquid state devices. During this evolution, the copper complex molecules present in the ele...

Photovoltaic performance of solar cells sensitized with indoline D205 dye and its new derivative comprising alkoxysilyl anchoring unit (D205Si) in the [Cu(tmby)2](TFSI)2/1 (tmby = 4,4’,6,6’-tetramethyl-2,2’-bipyridine, TFSI = bis(trifluoromethane)sulfonimide) redox couple mediated systems, were studied in the presence of various titania/dye/electro...

Dye-sensitized solar cells (DSSCs) have a great potential to expand the area of photovoltaics towards portable or indoor applications. Since the dye is one of the most costly components in the device, it is always of interest to find ways to lower its associated cost. Here, we propose the co-sensitization technique as a simple and effective solutio...

The authors express their sincere apologies to all readers of abovementioned article as mistakes were found upon discussion of the article with colleagues [...]

Photovoltaic performances of solar cells sensitized with indoline D205 dye1 and its novel derivative comprising alkoxysilyl anchoring unit (D205Si) in the [Cu(tmby)2](TFSI)2/1 (tmby = 4,4’,6,6’-tetramethyl-2,2’-bipyridine)2 redox couple mediated systems, were studied in the presence of titania| dye| electrolyte interface modifications - Cucurbit[7]...

Due to ligand scrambling, the synthesis and investigation of the properties of heteroleptic Cu(I) complexes can be a challenging task. In this work, we have studied the optical and electrochemical properties of a series of homoleptic complexes, such as [Cu(dbda)2]+, [Cu(dmp)2]+, [Cu(Br-dmp)2]+, [Cu(bcp)2]+, [Cu(dsbtmp)2]+, [Cu(biq)2]+, and [Cu(dap)...

The Cover Feature shows a donor–acceptor‐functionalized boron subphthalocyanine (SubPc) anchored onto TiO2 in a dye‐sensitized solar cell. The synthesis, optical and electrochemical properties, and device performances of a series of such SubPc derivatives are presented. More information can be found in the Article by H. Gotfredsen et al.

In order to sustainably support its ever-increasing energy demand, human society will have to harvest renewable energy wherever and whenever possible. When converting light to electricity, silicon solar cells are the technology of choice to harvest direct sunlight due to their high performance and continuously dropping price. For diffused light and...

Dye‐sensitized solar cells (DSSCs) are based on molecular and nanometer‐scale components. Record cell efficiencies of 12%, promising stability data, and means of energy efficient production methods have been accomplished. As selling points for the DSSC technology, the prospect of low‐cost investments and fabrication are key features. DSSCs offer th...

The conventional liquid dye-sensitized solar cell (l-DSC) is a photoelectrochemical system with a liquid redox electrolyte. Replacement of the liquid electrolyte with a solid-state hole transporting material (HTM) has several advantages: dye desorption is prevented, liquid leakage or evaporation cannot occur, and, finally, a solid-state device is m...

The recombination of injected electrons with oxidized redox species and regeneration behavior of copper redox mediators are investigated for four copper redox mediators, Cu(II/I) (dmby)2TFSI2/1 (dmby = 6,6′-dimethyl-2,2′-bipyridine), Cu(II/I) (tmby)2TFSI2/1 (tmby = 4,4′,6,6′- tetramethyl-2,2′-bipyridine), Cu(II/I) (eto)2TFSI2/1 (eto=4-ethoxy-6,6'-d...

Boron subphthalocyanines (SubPcs) are attractive as light‐harvesters in photovoltaics devices. Here we present the synthesis, optical and electrochemical properties, and device performances of a series of donor‐acceptor functionalized SubPc derivatives incorporating a carboxylic acid for anchoring onto TiO2. Liquid‐ and solid‐state dye‐sensitized s...

Substituted derivatives of hydroquinone/benzoquinone were studied as organic redox mediators in the electrolyte for dye-sensitized solar cells (DSSCs). Thus, di-tert-butylhydroquinone (DTHQ), thymohydroquinone (ThymHQ) and phenylhydroquinone (PhHQ), were combined with their oxidized counterparts to form the pairs DTHQ/DTBQ, ThymHQ/ThymBQ, and PhHQ/...

In dye-sensitized solar cells (DSCs), the redox mediator is responsible for the regeneration of the oxidized dye and for the hole transport towards the cathode. Here, we introduce new copper complexes with tetradentate 6,6′-bis(4-(S)-isopropyl-2-oxazolinyl)-2,2′-bipyridine ligands, Cu(oxabpy), as redox mediators. Copper coordination complexes with...

In perovskite solar cells (PSCs), the most commonly used hole transport material (HTM) is spiro‐OMeTAD, which is typically doped by metalorganic complexes, for example, based on Co, to improve charge transport properties and thereby enhance the photovoltaic performance of the device. In this study, we report a new hemicage‐structured iron complex,...

Novel highly active, optically-transparent electrode catalyst containing Pt, PtOx, graphene oxide and stacked graphene platelet nanofibers is developed for a cathode of Cu(II/I)-mediated dye-sensitized solar cells. The catalyst layer is deposited on a FTO substrate, which thus becomes smoother than the parent FTO, but the button-like Pt/PtOx nanopa...

Solid-state dye-sensitized solar cells currently suffer from issues such as inadequate nanopore filling, low conductivity and crystallization of hole-transport materials infiltrated in the mesoscopic TiO2 scaffolds, leading to low performances. Here we report a record 11% stable solid-state dye-sensitized solar cell under standard air mass 1.5 glob...

Supplementary Figures, Supplementary Table and Supplementary References

The scientific progress in the field of dye-sensitized solar cells (DSCs) is marked by a recent number of important breakthroughs. DSCs provide a technically and economically credible alternative concept to present-day p–n junction photovoltaic devices. Relentless efforts helped to achieve high efficiencies with DSCs. Some of the major progress was...

Three Cu(II/I)-phenanthroline and Cu(II/I)-bipyridine redox mediators are studied on various electrodes and in variety of electrolyte solutions using cyclic voltammetry and impedance spectroscopy on symmetrical dummy cells. Graphene-based catalysts provide comparably high activity to PEDOT, and both catalysts outperform the activity of platinum. Th...

The Inside Cover picture illustrates a new redox mediator based on the cobalt hemicage complexes. The highly pre-organized complexes show considerable thermal and light stability in DSCs. The artist of the cover picture is Sigríđur Huld Ingvarsdóttir. More information can be found in the Full Paper by M. Freitag et al. on page 3845 in Issue 23, 201...

A new class of dye-sensitized solar cells (DSSCs) using the hemicage cobalt-based mediator [Co(ttb)]2+/3+ with the highly preorganized hexadentate ligand 5,5′′,5′′′′-((2,4,6-triethyl benzene-1,3,5-triyl)tris(ethane-2,1-diyl))tri-2,2′-bipyridine (ttb) has been fully investigated. The performances of DSSCs sensitized with organic D-π-A dyes utilizing...

Until recently, there have been no viable alternatives for Spiro-OMeTAD as a hole-transport material (HTM) for dye-sensitized solar cells (DSSC). ¹ In this study we show that copper phenanthroline complexes in the solid phase can act as efficient molecular hole conductors in DSSCs. Normally, DSSCs utilize a liquid redox electrolyte, but there are s...

The most commonly used redox mediators in dye-sensitized solar cells (DSCs), iodide/triiodide and cobalt trisbipyridine ([Co(bpy)3]2+/3+), were successfully replaced by bis(2,9-dimethyl-1,10-phenanthroline)copper(I/II) ([Cu(dmp)2]1+/2+). The use of the copper complex based electrolyte led to an exceptionally high photovoltaic performance of 8.3% fo...

Copper phenanthroline complexes in the solid phase can act as efficient molecular hole transporting material (HTM) for hybrid solar cells. We prepared solid-state dye-sensitized solar cells with the organic dye LEG4 and bis(2,9-dimethyl-1,10-phenanthroline)copper(I/II) (Cu(dmp)2) and achieved power conversion efficiencies more than 8% under 1000 W...

A viologen derivative, 1,1'-di-p-tolyl-(4,4'-bipyridine)-1,1'-diium dichloride (DTV(2+)), was studied in solution and encapsulated in cucurbit[7]uril (CB7), a macrocyclic host. Upon encapsulation, DTV(2+) exhibited dramatically enhanced fluorescence. Aqueous solutions of DTV(2+) were weakly fluorescent (Φ = 0.01, τ < 20 ps), whereas the emission of...

Coumarins C-153, C-480, and C-1 formed 1:2 (guest:host) complexes with a water-soluble cavitand having eight carboxylic acid groups (OA) in aqueous borate buffer solution. The complexes were photoexcited in the presence of electron acceptors (methyl viologen, MV(2+), or TiO(2)) to probe the possibility of electron transfer between a donor and an ac...

A recent and promising development in the field of renewable energy is the use of molecular containers (cyclodextrins, cucurbiturils, Cram-type hosts, and calixarenes) to bind encapsulated chromophores or redox-active compounds to the surface of TiO2 nanoparticles and other nanostructured wide bandgap metal oxide semiconductors. The host provides a...

Methylviologen (1,1'-dimethyl-4,4'-bipyridinium dichloride, MV(2+), 1) and a newly synthesized viologen derivative (1-methyl-1'-p-tolyl-4,4'-bipyridinium dichloride, MTV(2+), 2) were encapsulated in a macrocyclic host, cucur[7]bituril, CB[7]. The complexes MV(2+)@CB[7] and MTV(2+)@CB[7] were physisorbed on the surface of TiO(2) nanoparticles films....

The Research Center System Safety of the Berlin University of Technology conducted a research project on the analysis of Human Factors (HF) aspects in incident reported by German Nuclear Power Plants. Based on psychological theories and empirical studies a classification scheme was developed which permits the identification of human involvement in...