Jan M Kroon

ECN part of TNO | ECN

The cover image is based on the Research Article A European proficiency test on thin‐film tandem photovoltaic devices by Elena Salis et al., https://doi.org/10.1002/pip.3322.

A round‐robin proficiency test (RR PT) on thin‐film multi‐junction (MJ) photovoltaic (PV) cells was run between 13 laboratories within the European project CHEETAH. Five encapsulated PV cells were circulated to participants for being tested at Standard Test Conditions (STC). Three cells were a‐Si/μc‐Si tandem PV devices, each of which had a differe...

Accurate characterization and reporting of organic photovoltaic (OPV) device performance remains one of the important challenges in the field. The large spread among the efficiencies of devices with the same structure reported by different groups is significantly caused by different procedures and equipment used during testing.The presented article...

We present an outdoor interlaboratory stability study of fully printed and coated indium-tin-oxide (ITO)-free polymer solar cell modules in JNCASR Bangalore (India), ECN (Holland), and DTU (Denmark) carried over more than 1 year. The modules comprising a fully printed and coated stack (Ag grid/PEDOT:PSS/ZnO/P3HT:PCBM/PEDOT:PSS/Ag grid) were prepare...

Solar cells are generally optimised for operation under AM1.5 100 mW cm(-2) conditions. This is also typically done for polymer solar cells. However, one of the entry markets for this emerging technology is portable electronics. For this market, the spectral shape and intensity of typical illumination conditions deviate considerably from the standa...

Indium-tin-oxide-free (ITO-free) polymer solar cells with composite electrodes containing current-collecting grids and a semitransparent poly(3,4-ethylenedioxythiophene):polystyrenesulfonate) (PEDOT:PSS) conductor are demonstrated. The up-scaling of the length of the solar cell from 1 to 6 cm and the effect of the grid line resistance are explored...

Five different indium‐tin‐oxide free (ITO‐free) polymer solar cell architectures provided by four participating research institutions that all presented a laboratory cell performance sufficient for use in mobile and information and communication technology (ICT) were evaluated based on photovoltaic performance and lifetime tests according to the IS...

Polymer solar cells may be applied in portable electronic devices, where light intensity and spectral distribution of the illuminating source can be very different compared to outdoor applications. As the power output of solar cells depends on temperature, light intensity and spectrum, the design of the module must be optimized for the specific ill...

Organic photovoltaic modules have been evaluated for their integration in mobile electronic applications such as a laser pointer. An evaluation of roll-to-roll processed indium and silver free polymer solar cells has been carried out from different perspectives: life cycle assessment, cost analysis and layer quality evaluation using inline optical...

Polymer solar cells offer a promising low cost alternative in photovoltaics if the expensive ITO electrode can be omitted. Recently an alternative based on highly conductive PEDOT:PSS in combination with current collecting grids was developed. Electrical modeling is carried out to optimize the grid pattern in these polymer solar cells. The basic in...

ITO-free organic solar cells with ink-jet printed current collecting grids and high conducting PEDOT:PSS as a composite anode are demonstrated. Inkjet printed current collecting grids with different cross-sectional areas have been investigated. The effect of the width and height of the grid lines and busbars has been measured and modeled by direct...

In the present review, the main degradation mechanisms occurring in the different layer stacking (i.e. photoactive layer, electrode, encapsulation film, interconnection) of polymeric organic solar cells and modules are discussed. Bulk and interfacial, as well as chemical and physical degradation mechanisms are reviewed, as well as their implication...

Indium-tin-oxide (ITO) free polymer solar cells prepared by ink jet printing a composite front electrode comprising silver grid lines and a semitransparent PEDOT:PSS conductor are demonstrated. The effect of grid line density is explored for a large series of devices and a careful modeling study enabling the identifi cation of the most rational gri...

The image depicts indium tin oxide (ITO)-free polymer solar cells, prepared by ink jet printing a composite front electrode comprising silver grid lines and a semitransparent PEDOT:PSS conductor. On page 103, Y. Galagan et al. demonstrate the effect of grid-line density on the performance of these current-collecting grids for ITO-free polymer solar...

This article describes how the Solliance Organic PhotoVoltaics (OPV) shared research Program addresses efficiency, lifetime and production costs for (near) future OPV applications. The balance of these three parameters depends of the envisaged application, but at the end, OPV should be able to compete somehow with Si PV in the future. Efficiency im...

Electrical and luminescence characterization was performed on 16 dye sensitized solar cells with different formulations, from different industrial and academic sources. Most of the cells were fabricated in pre-industrial pilot lines. The cells were put through a light soaking period up to 150 hours and then re-characterized. The results show the co...

a b s t r a c t The presence of a transparent conductive electrode such as indium tin oxide (ITO) limits the reliability and cost price of organic photovoltaic devices as it is brittle and expensive. Moreover, the relative high sheet resistance of an ITO electrode on flexible substrates limits the maximum width of a single cell. We have developed a...

In order to reach the objective of low-cost, large area organic photovoltaic systems, we build up a knowledge base concerning the influence of process conditions on the performance of polymer solar cells. A large area solar cell module, with roll-to-roll coated PEDOT:PSS and photoactive layers (based on P3HT:[C60]PCBM blend) on a flexible substrate...

To reduce the costs of polymer solar cells it is important to develop a fully solution processed route. Although several successful generic routes to solution processed hole collecting electrodes have been shown, this is not the case for the electron collecting electrode of polymers cells, as it is hard to find a solution processable low workfuncti...

The presence of a brittle and expensive ITO electrode is a limiting factor towards low cost OPV modules. Moreover, ITO layers on PET or PEN substrates are typically characterized by relatively high sheet resistances and the presence of large amounts of spikes that lead to efficiency losses. We have developed an alternative for the ITO anode, based...

To investigate the viability of cyclometalation as a general tool in the design of new sensitizers for dyesensitized solar cells, a series of (cyclometalated) ruthenium complexes was prepared. To this purpose we have prepared the carboxylate-functionalized 2,20:60,200-terpyridine (tpy)-based tridentate ligands 40-ethoxycarbonyl-2,20:60,200-terpyrid...

The presence of a transparent conductive electrode such as indium tin oxide (ITO) limits the reliability and cost price of organic photovoltaic devices as it is brittle and expensive. Moreover, the relative high sheet resistance of an ITO electrode on flexible substrates limits the maximum width of a single cell. Holst Centre and ECN have developed...

A round robin for the performance of roll-to-roll coated flexible large-area polymer solar-cell modules involving 18 different laboratories in Northern America, Europe and Middle East is presented. The study involved the performance measurement of the devices at one location (Risø DTU) followed by transportation to a participating laboratory for pe...

Although the workhorse of the photovoltaic industry is still the silicon wafer, accounting for 90% of the market, it was early recognized that other semiconductors could make efficient solar cells. Organic-based photovoltaic technology has demonstrated the ability to cross the 10% efficiency barrier and is expected to eventually present lower costs...

The inclusion of metal-oxide layers in polymer solar cells enables the fabrication of a series of unconventional device architectures. These devices include: semi-transparent polymer solar cells, devices with inverted polarity, as well as devices with air stable electrodes. A proof-of-principle of these devices is presented. The anticipated benefit...

Tandem solar cells, in which two individual cells are stacked on top of each other, offer the potential to increase the efficiency significantly compared to a single cell on the same area. To reach maximum efficiency, each cell in the stack must have a distinctive spectral response and the current in each cell must be similar. This requires smart s...

The electro-optical properties of thin films of electron donor-acceptor blends of a fluorene copolymer (PF10TBT) and a fullerene derivative (PCBM) were studied. Transmission electron microscopy shows that in these films nanocrystalline PCBM clusters are formed at high PCBM content. For all concentrations, a charge transfer (CT) transition is observ...

We discuss the materials challenges for increasing cell efficiencies of polymer solar cells via the route of stacking several cells on top of each other in multi-junction solar cells. For such cells, the recombination layer between the two sub cells is crucial. Typically, the recombination layer consists of a semi-transparent n-and p-type semicondu...

This review describes recent advances in the research on dye-sensitized solar cells. After a brief discussion of the general operation principles and a presentation of record efficiencies, stability data and key technology drivers, current trends will be reviewed. The focus of this review is on materials development (sensitizers, nanostructured oxi...

This paper gives an overview of the status of photovoltaic devices based on blends of semiconducting polymers. The polymer blends form the bulk heterojunction in these photovoltaic devices. The fundamental mechanisms governing the performance of these devices are discussed as well as the specificities of these all-polymer solar cells. The morpholog...

The photovoltaic performance of liq. electrolyte and solid-state dye sensitized solar cells, employing a squarilium methoxy cyanide dye, are evaluated in terms of interfacial electron transfer kinetics. Dye adsorption to the metal oxide film resulted in a mixed population of aggregated and monomeric sensitizer dyes. Emission quenching data, coupled...

We have used optical modeling to calculate whether optical absorption and corresponding current densities in solar cells consisting of PF10TBT:PCBM (1:4) can be enhanced, either in single junctions by applying optical spacers or by going to a tandem structure. The current densities are calculated from the optical absorption using experimentally det...

Cyclometalated ruthenium complexes of [Ru(C--arrow--N) (N--N--N)] configuration are a promising new class of molecular sensitizers for dye-sensitized solar cells, as a result of their broad and red-shifted visible absorption in comparison to the analogous [Ru(N--N--N)2] type coordinative complexes.

A power conversion efficiency of 4.2% (AM1.5, 1000 W / m ² ) is measured for an organic solar cell based on an active layer of an alternating copolymer, containing a fluorene and a benzothiadiazole unit with two neighboring thiophene rings, and a fullerene derivative. Using optical modeling, the absorption profile in the active layer of...

We report the synthesis, characterization, and electrochemical properties of ten new fullerene derivatives for usage in organic solar cells. The phenyl ring of PCBM was substituted with electron-donating and electron-withdrawing substituents to study their influence on the LUMO level of the parent fullerene. We varied the LUMO level over a range of...

This paper presents an overview of the research carried out by a European consortium with the aim to develop and test new and improved ways to realize dye-sensitized solar cells (DSC) with enhanced efficiencies and stabilities. Several new areas have been explored in the field of new concepts and materials, fabrication protocols for TiO2 and scatte...

We report one of the highest power conversion efficiencies (PCE) of 4.2 % (AM1.5, 1000 W/m2) for an organic polyfluorene:fullerene solar cell. Optical modeling was used to calculate whether the optical absorption and thus the short circuit current in such a solar cell can be enhanced, either in single junctions by varying the active layer thickness...

In this study, the influence of the TiCl(4) post-treatment on nanocrystalline TiO(2) films as electrodes in dye-sensitized solar cells is investigated and compared to nontreated films. As a result of this post-treatment cell efficiencies are improved, due to higher photocurrents. On a microscopic scale TiO(2) particle growth on the order of 1 nm is...

An organic bulk heterojunction photovoltaic device based on a blend of two conjugated polymers, a polyphenylenevinylene as the electron donor and a red emitting polyfluorene as the acceptor, is presented with a maximum external quantum efficiency of 52% at 530 nm and a power conversion efficiency, measured under AM1.5G, 100 mW/cm2 conditions, of 1....

This paper discusses the characterization and optimization of organic solar cells based on a bulk heterojunction consisting of an alternating copolymer, containing a fluorene and a benzathiadiazole unit with two neighboring thiophene rings, and a fullerene derivative (PCBM). The resulting power conversion efficiency amounts 3.9±0.2 % (AM1.5, 100 mW...

Recently, there has been growing interest in photovoltaic cells based on bulk heterojunctions of ZnO and a conjugated polymer. In this work, the photophysical processes in a hybrid film of ZnO with MDMO-PPV were studied by means of optical absorption spectroscopy and microwave photoconductivity measurements. Films were prepared from a blend of a Zn...

We describe a new method towards bulk-heterojunction hybrid polymer solar cells based on composite films of zinc oxide (ZnO) and a conjugated polymer poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylene vinylene] (MDMO-PPV). Spin-coating diethylzinc as a ZnO precursor and MDMO-PPV from a common solvent at 40 % humidity and annealing at 110 degre...

We describe a simple and new method to create hybrid bulk heterojunction solar cells consisting of ZnO and conjugated polymers. A gel-forming ZnO precursor, blended with conjugated polymers, is converted into crystalline ZnO at temperatures as low as 110 °C. In-situ formation of ZnO in MDMO-PPV leads to a quenching of the polymer photoluminescence....

In hybrid polymer photovoltaics, conjugated polymers are combined with wide bandgap metal oxide semiconductors like TiO2 or ZnO. Reported maximum power conversion efficiencies (PCE) at AM1.5G conditions for a hybrid polymer bulkheterojunction device are up to 1.6 %. In this paper we report on the current-voltage characteristics of bi-layer devices...

We present a highly fluorescent polymer poly[2,7-(9,9’-dioctylfluorene)-alt-l,4-bis(1-cyanovinyl-2-thienyl)-2-methoxy-5-(3,7-dimethyloctyloxy)phcnylene] (PF1CVTP), that was lbund to perform exceptionally welI as electron acceptor in polymer photovoltaic devices when mixed with poly(2-methoxy-5-(3,7-dimethyloctyloxy)-l,4-phenylenevinylene) (MDMO-PPV...

We report a comparison of charge transport and recombination dynamics in dye-sensitized solar cells (DSSCs) employing nanocrystalline TiO(2) and SnO(2) films and address the impact of these dynamics upon photovoltaic device efficiency. Transient photovoltage studies of electron transport in the metal oxide film are correlated with transient absorpt...

Transmission electron microscopy and electron diffraction are used to study the changes in morphology of composite films of poly(3-hexylthiophene) (P3HT) and a methanofullerene derivative (PCBM) in bulk heterojunction solar cells. Thermal annealing produces and stabilizes a nanoscale interpenetrating network with crystalline order for both componen...

Hydrolysis of titanium(IV) isopropoxide (TTIP) is a well-known method for the fabrication of TiO2. Normally it is made via a sol–gel reaction in the presence of water. In this paper we report on the preparation of flat TiO2 films for conjugated polymer/TiO2 photovoltaic cells, from a TTIP/isopropanol solution. It is shown that the morphological str...

We report a study of the optimization of power conversion efficiency in hybrid solar cells based on nanostructured titanium dioxide and a poly[2-(2-ethylhexyloxy)-5-methoxy-1,4-phenylenevinylene] (MEH-PPV) based conjugated polymer. Charge collection efficiency is enhanced by introducing a poly(ethylenedioxythiophene)/polystyrene sulphonate (PEDOT)...

The effect of annealing blends of poly(2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene) (MDMO-PPV) and a poly(cyanoether phenylenevinylene) (PCNEPV) on the photoconductivity is studied. Charge carriers are generated by pulsed-laser excitation and their mobility and decay kinetics are monitored using time-resolved microwave conductivity (...

Over the last few years, measurements from many labs have allowed the development of a reasonably complete picture of the kinetics and electrostatics (band alignments and fields) of dye sensitized solar cells based on nanoporous oxide films (e.g. TiO₂, ZnO). With some modifications, this model incorporates both electrolyte and solid-stat...

The authors report an anal. of the influence of acid/base conditions employed in the synthesis of TiO2 nanoparticles upon the performance of dye sensitized photoelectrochem. solar cells fabricated from these particles. The functional properties of the TiO2 nanoparticles in these devices are studied by potential step chronoamperometry, transient las...

A summary is given of the multidisciplinary research efforts in the Netherlands in the field of polymer-based photovoltaics (PV) between 1997 and 2005. It has been shown that different types of bulk heterojunctions namely polymer:fullerene, polymer:polymer and polymer:metal-oxide cells can be made in a laboratory environment with relatively simple...

This study comprises the behavior of dye-sensitized nanocrystalline TiO2 solar cells (nc-DSC) under various testing conditions regarding accelerated aging. nc-DSCs are potentially vulnerable to various kinds of degradation. The cell performance is seriously decreased upon heat treatments, despite the fact that leakage of the electrolyte liquid is e...

Photovoltaic properties of solution-processed semiconducting polymer blends have been studied. It is demonstrated that photoinduced charge transfer occurs in binary mixtures of poly[2-methoxy-5-(3,7-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV) and poly-[oxa-1,4-phenylene-(1-cyano-1,2-vinylene)-(2-methoxy-5-(3,7-dimethyloctyloxy)-1,4-phenylen...

The transient photoconductivity of blends of a highly soluble C60 derivative (PCBM) and a dialkoxy-phenylene-vinylene polymer (MDMO-PPV) has been studied using the electrodeless flash-photolysis time-resolved microwave conductivity technique (FP-TRMC). Films approximately 100 nm thick on a quartz substrate were prepared by spin-coating PCBM/PPV sol...

Hybrid TiO2:polymer photovoltaic cells were made from mixtures of titanium(IV) isopropoxide and poly[2-methoxy-5-(3′,7′-dimethyloctyl)-p-phenylene vinylene] (MDMO-PPV) or poly(3-octyl thiophene) (P3OT) via hydrolysis in air. Cells were made with varying titanium(IV) isopropoxide:polymer ratios. Current–voltage measurements (at 0.7–0.8 sun equivalen...

Polymer bulk hetero junction solar cells were made from poly(2-methoxy-5-(3,7-dimethyloctyloxy)-1,4-phenylene-vinylene) (MDMO-PPV) as donor and poly(cyanoetherphenylenevinylene) (PCNEPV) derivatives as acceptor material. In this paper we start out with discussing the synthesis of the materials. Subsequently, the main issues concerning the devices a...

Wegen der starken Absorption von sichtbarem Licht durch [70]Fulleren-Derivate erreicht man mit ihnen als Elektronenacceptor in Polymer-Dünnschichtsolarzellen hohe Photoströme. Ein Poly(p-phenylenvinylen) mit eingelagertem [70]PCBM erzielt bei der Umwandlung einfallender Photonen in Strom eine Effizienz von 66 %. Der Grund für diese hohen Photoström...

Solar cells prepared using the alternating copolymer shown in the Figure blended with a C-60 derivative (PCBM) are demonstrated to have a high performance, with a power conversion efficiency of 2.2 % under simulated solar light. The molecular weight of the polymer is low due to limited solubility, and films of the polymer exhibit red-shifted absorp...

At ECN Solar Energy, the dye sensitised solar cell (nc-DSC) is developed from laboratory scale to the pre-pilot module stage. The process line with mechanised equipment for 10/spl times/10 and 7.5/spl times/10 cm/sup 2/ devices is presented. Power conversion efficiencies of 6% obtained for cell-areas of 2.5 cm/sup 2/ are successfully translated to...

A fully operational baseline consisting of dedicated equipment to process nanocrystalline dye-sensitized solar cell devices has been installed at ECN. This baseline focuses on the production of glass/glass devices with dimensions up to 10×10 cm2. Present power conversion efficiencies of 6% obtained for cell areas of 2ċ5 cm2 are successfully transla...

The interaction of an acid-functionalized oligo(p-phenylenevinylene) (OPV3-COOH) with nanocrystalline TiO2 has been studied as a model for semiconducting polymer–inorganic material hybrid solar cells. Langmuir adsorption studies show that the monolayer coverage of OPV3-COOH on nc-TiO2 results in 35% filling of the nanopores. Photoluminescence quenc...

Combining conjugated poylmers and TiO2 in hybrid bulk-heterojunctions is a promising method for producing novel solar cells. Here TiO2 is introduced into a poly(p-phenylene vinylene) layer. Nanometer-scale phase separation allows efficient photoinduced charge transfer between the two components. The films can be used as the active layer in a photov...

The current–voltage characteristics of methanofullerene [6,6]-phenyl C61-butyric acid methyl ester (PCBM)-based devices are investigated as a function of temperature. The occurrence of space–charge limited current enables a direct determination of the electron mobility. At room temperature, an electron mobility of μe = 2 × 10–7 m2 V–1 s–1 has been...

We report on an accurate indoor determination of the power conversion efficiency under standard test conditions [1000 W/m2, AM1.5 global (IEC 904-3), 25°C] for an organic photovoltaic device based on a bulk heterojunction of a conjugated polymer and a methanofullerene. AM1.5 efficiencies up to 2.55% are achieved for cell areas ≤1.0 cm2. Systematic...

We report on the temperature dependence of various photovoltaic device parameters of solar cells, fabricated from interpenetrating networks of conjugated polymers with fullerenes, in the wide temperature range of their possible operating conditions (25–60 °C). The open-circuit voltage was found to decrease linearly with increasing temperature. For...

Accelerated ageing tests on large numbers of nanocrystalline dye-sensitised solar cells (nc-DSC) show that, to first order, separation between the effects of the stresses of visible light soaking, UV illumination and thermal treatment on long-term stability is possible. The corresponding mechanisms are electrochemical, photochemical and purely chem...

To be able to commercialize the dye-sensitised solar cell (DSC) technology for large area power applications it needs to be clear what module life-times can be obtained. Therefore, the long term stability of DSCs is investigated. Accelerated tests are performed in order to determine the lifetime of DSCs. Stability results over 10000 h were obtained...

Dye-sensitized nanocrystalline TiO2 solar cells (nc-DSCs) are based on a fundamentally different working principle than solar cells based on semiconductors. This could have implications for the characterization of nc-DSCs. In this study a comparison is made between two methods for determination of the spectral response of nc-DSCs. The standard meth...