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We present results from an installation of fully roll-to-roll printed and coated polymer solar cell modules in a greenhouse environment over the course of roughly 2 years (650 days). We explored two different device architectures based on either fully carbon-based electrodes or silver nanowire (AgNW)-based electrodes and two different barrier materials. We followed the ISOS protocols while studying the devices in three different greenhouse conditions in the Netherlands and compared to reference devices mounted outdoors in Denmark tested according to ISOS-O-1 and ISOS-O-2. We studied each condition and type in multiples to obtain acceptable statistics and found that the AgNW-based devices performed best in terms of stability. [ABSTRACT FROM AUTHOR]

Vanadium pentoxide has been proposed as a good alternative hole transport layer for improving device lifetime of organic photovoltaics. The article presents a study on the optimization of slot-die-coated vanadium oxide films produced with a roll coating machine with the aim of achieving scalable organic solar cells and photo-detectors with improved performance. The effect of different diluents on the electrical properties of the vanadium oxide films is investigated, and methodologies for efficient interfacing of the anode are studied. Furthermore, the lifetime of the cells with incorporated vanadium oxide is investigated employing different encapsulation methods. Finally, an application of the manufactured scalable devices in proximity sensors is demonstrated using a 3D-printed scaffold. [ABSTRACT FROM AUTHOR]

In an effort to understand recent results showing differences between the power conversion efficiencies of lead halide (CH3NH3PbI3−xClx) solar cells on glass versus flexible substrates, this study investigates the influence that substrate and processing methods have on morphological and crystallographic development. Using our in situ slot-die micro roll-to-roll coater setup, we measured small and wide angle X-ray scattering in grazing incidence while the material dried, enabling us to follow the crystallization from just after the deposition and up to 25 minutes later. The data showed differing crystallographic developments between the substrates, especially seen through the behaviour of a crystalline precursor which survived longer on the flexible substrates than on glass. Additionally, the common degradation product PbI2 was absent on the thickest flexible substrate. This leads us to conjecture that the flexible substrates absorb part of the solvent, thereby delaying evaporation and changing the solvent environment around the perovskite. As a further test, we produced solar cells with the same substrates and confirmed that the ones made on flexible substrates performed worse than those made on glass, but that when including an ITO layer in the stack it seemed to act as a buffer, whereby the solar cell performance was improved. [ABSTRACT FROM AUTHOR]

Silver nanowires (AgNWs) were prepared on a 5 g scale using either the well-known batch synthesis following the polyol method or a new flow synthesis method. The AgNWs were employed as semitransparent electrode materials in organic photovoltaics and compared to traditional printed silver electrodes based on micron sized silver flakes using life cycle analysis and environmental impact analysis methods. The life cycle analysis of AgNWs confirms that they provide an avenue to low-impact semitransparent electrodes. We find that the benefit of AgNWs in terms of embodied energy is less pronounced than generally assumed but that the toxicological and environmental benefits are significant. [ABSTRACT FROM AUTHOR]

PBDTTTz-4 is employed in the ambient manufacturing of fully Roll-to-Roll organic solar cell modules. Modules are manufactured using a novel silver nanowire electrode or a previously reported carbon electrode. The average PCE of carbon modules (3.07%) and AgNW modules (1.46%) shows that PBDTTTz-4 is a good candidate for upscaling. Stability measurements following the ISOS standards are used to compare the lifetime of the different modules. In all tests but one, the carbon modules are less stable. The higher stability of AgNW is attributed to the removal of the PEDOT:PSS in the front electrode. Finally during indoor light tests, a new degradation phenomenon is observed where bubbles are formed inside the modules contrary to previous reports of bubble formation by thermal expansion of trapped gas inside the barrier. [ABSTRACT FROM AUTHOR]

A comprehensive outdoor study of polymer solar cells and modules for duration of one year was conducted. Different sample geometries and encapsulations were employed in order to study the spread in the lifetimes. The study is a complimentary report to previous work that focused on indoor ageing tests. Comparison of the indoor and outdoor lifetimes was performed by means of the o-diagram, which constitutes the initial steps towards establishing a method for predicting the lifetime of an organic photovoltaic device under real operational conditions based on a selection of accelerated indoor tests. Acceleration factors were determined using the ISOS-protocols, which enabled reproducible data acquisition between different laboratories and operators within the OPV community. A semi-automatic filtering method was employed for processing data acquired in outdoor tests. It was found that the lifetime of the samples tested under outdoor conditions was somewhere between the lifetimes of samples measured in accelerated indoor test conditions of damp heat and light soaking (ISOS-D-3 and ISOS-L-2) and in moderate indoor test conditions (shelf life and high temperature storage). The presented results reveal that while the accelerated ageing studies reveal days and weeks of lifetime for the studied samples, in outdoor real operational conditions the samples demonstrate stability up to months and seasons. [ABSTRACT FROM AUTHOR]

The effect of substituting lead with tin in perovskite‐based solar cells (PSCs) has shows that lead is preferred over tin by a lower cumulative energy demand. The results, which also include end‐of‐life management, show that a recycling scenario that carefully handles emission of lead enables use of lead in PSCs with little environmental impact. All other scenarios result in catastrophic emission of lead to the environment that would spell an end to widespread use of lead in PSCs. [ABSTRACT FROM AUTHOR]

A scaling effort on perovskite solar cells is presented where the device manufacture is progressed onto flexible substrates using scalable techniques such as slot-die roll coating under ambient conditions. The printing of the back electrode using both carbon and silver is essential to the scaling effort. Both normal and inverted device geometries are explored and it is found that the formation of the correct morphology for the perovskite layer depends heavily on the surface upon which it is coated and this has significant implications for manufacture. The time it takes to form the desired layer morphology falls in the range of 5-45 min depending on the perovskite precursor, where the former timescale is compatible with mass production and the latter is best suited for laboratory work. A significant loss in solar cell performance of around 50% is found when progressing to using a fully scalable fabrication process, which is comparable to what is observed for other printable solar cell technologies such as polymer solar cells. The power conversion efficiency (PCE) for devices processed using spin coating on indium tin oxide (ITO)-glass with evaporated back electrode yields a PCE of 9.4%. The same device type and active area realized using slot-die coating on flexible ITO-polyethyleneterphthalate (PET) with a printed back electrode gives a PCE of 4.9%. [ABSTRACT FROM AUTHOR]

Silver nanowires (AgNWs) and zinc oxide (ZnO) are deposited on flexible substrates using fast roll-to-roll (R2R) processing. The AgNW film on polyethylene terephthalate (PET) shows >80% uniform optical transmission in the range of 550-900 nm. This electrode is compared to the previously reported and currently widely produced indium-tin-oxide (ITO) replacement comprising polyethylene terephthalate (PET)|silver grid|poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)|ZnO known as Flextrode. The AgNW/ZnO electrode shows higher transmission than Flextrode above 490 nm in the electromagnetic spectrum reaching up to 40% increased transmission at 750 nm in comparison to Flextrode. The functionality of AgNW electrodes is demonstrated in single and tandem polymer solar cells and compared with parallel devices on traditional Flextrode. All layers, apart from the semitransparent electrodes which are large-scale R2R produced, are fabricated in ambient conditions on a laboratory roll-coater using printing and coating methods which are directly transferrable to large-scale R2R processing upon availability of materials. In a single cell structure, Flextrode is preferable with active layers based on poly-3-hexylthiophene(P3HT):phenyl-C61-butyric acid methylester (PCBM) and donor polymers of similar absorption characteristics while AgNW/ZnO electrodes are more compatible with low band gap polymer-based single cells. In tandem devices, AgNW/ZnO is more preferable resulting in up to 80% improvement in PCE compared to parallel devices on Flextrode. [ABSTRACT FROM AUTHOR]

We report on the stability of large-area (100 cm2), low-cost, indium-tin-oxide (ITO)-free modules over two years (>17 500 h) under outdoor operational conditions in Denmark and under indoor storage condition by following ISOS-O-3 and ISOS-D-2 protocols. Irrespective of the testing regimes (storage and outdoor), all modules maintain the maximum power point (MPP) above T80 (the duration over which a solar cell retains above 80 % of its initial MPP) over two years using a simple low-cost packaging barrier with a water vapor transmission rate (WVTR) of 0.04 g m−2 day−1, an oxygen transmission rate (OTR) of 0.01 cm3 m−2 bar−1 day−1, and a UV cut-off at 390 nm. Unlike previous studies, localized degradation through edges and contact points in the modules are not overwhelming even after more than two years; therefore, the differences in degradation under long-term outdoor and storage conditions could be probed. The results suggest that oxygen permeation may be mainly responsible for degradation under outdoor conditions, whereas WVTR has a larger bearing under storage conditions. [ABSTRACT FROM AUTHOR]

The results presented demonstrate how the screening of 104 light-absorbing low band gap polymers for suitability in roll coated polymer solar cells can be accomplished through rational synthesis according to a matrix where 8 donor and 13 acceptor units are organized in rows and columns. Synthesis of all the polymers corresponding to all combinations of donor and acceptor units is followed by characterization of all the materials with respect to molecular weight, electrochemical energy levels, band gaps, photochemical stability, carrier mobility, and photovoltaic parameters. The photovoltaic evaluation is carried out with specific reference to scalable manufacture, which includes large area (1 cm2), stable inverted device architecture, an indium-tin-oxide-free fully printed flexible front electrode with ZnO/PEDOT:PSS (poly(3,4-ethylenedioxythiophene):polystyrene sulfonate), and a printed silver comb back electrode structure. The matrix organization enables fast identification of active layer materials according to a weighted merit factor that includes more than simply the power conversion efficiency and is used as a method to identify the lead candidates. Based on several characteristics included in the merit factor, it is found that 13 out of the 104 synthesized polymers outperformed poly(3-hexylthiophene) under the chosen processing conditions and thus can be suitable for further development. [ABSTRACT FROM AUTHOR]

We describe and review how the scaling of printed energy technologies not only requires scaling of the input materials but also the machinery used in the processes. The general consensus that ultrafast processing of technologies with large energy capacity can only be realized using roll-to-roll methods is taken as a premise, and thus the progression from a highly successful laboratory technique (i.e., spin coating) to large-scale roll-to-roll equipment is described in terms of all of the intermediate steps that must be available to make the transfer possible. Spin coating is compatible with materials availability on the small scale and efficient scaling of equipment is a demanding task that must be performed in parallel with increasing materials availability. We outline that 3-5 processing platforms are necessary to efficiently take the laboratory technology to a version that represents the lower end of the industrial scale. The machinery bridges the gap through firstly achieving improved ink efficiency without surface contact, followed by better ink efficiency at higher speeds, and finally large-area processing at high speed with very high ink efficiency. [ABSTRACT FROM AUTHOR]

Solar textiles are highlighted as a future technology with transformative power within the fields of both textiles and solar cells provided that developments are made in critical areas. Specifically, these are fundamental solutions to materials and material combinations with mechanical stability and flexibility imposed by textile architectures, scientific solutions to achieve high carrier transport efficiency and optical transmission in a textile topology, technical solutions to controlling the physical disposition of the anode and cathode along with their specific and error-free contacting and, finally, practical solutions to fast and efficient manufacture and integration. The areas of application and the penetration of solar textiles into our everyday life are expected to be explosive pending efficient developments within these four key areas. A shortcoming in one or more of these will, however, lead to the solar textiles being banned to academic existence. [ABSTRACT FROM AUTHOR]

The realization of a complete tandem polymer solar cell under ambient conditions using only printing and coating methods on a flexible substrate results in a fully scalable process but also requires accurate control during layer formation to succeed. The serial process where the layers are added one after the other by wet processing leaves plenty of room for error and the process development calls for an analytical technique that enables 3D reconstruction of the layer stack with the possibility to probe thickness, density, and chemistry of the individual layers in the stack. The use of ptychography on a complete 12-layer solar cell stack is presented and it is shown that this technique provides the necessary insight to enable efficient development of inks and processes for the most critical layers in the tandem stack such as the recombination layer where solvent penetration in fully solution processed 12-layer stacks is critical in eleven of the steps. [ABSTRACT FROM AUTHOR]

As mass-produced, low-cost organic electronics enter our everyday lives, so does the waste from them. The challenges associated with end-of-life management must be addressed by careful design and carbon-based electrodes are central to these developments. Here, the reproducible production of vacuum-, indium tin oxide (ITO)-, and silver-free solar cells in a fully packaged form using only roll-to-roll processing is reported. Replacing silver with carbon as electrode material significantly lowers the manufacturing cost and makes the organic photovoltaic (OPV) modules environmentally safe while retaining their flexibility, active area efficiency, and stability. The substitution of silver with carbon does not affect the roll-to-roll manufacturing of the modules and allows for the same fast printing and coating. The use of carbon as electrode material is one step closer to the wide release of low-cost plastic solar cells and opens the door to new possible applications where silver recycling is not manageable. [ABSTRACT FROM AUTHOR]

The active layer crystallization during roll-to-roll coating of organic solar cells is studied in situ. We developed an X-ray setup where the coater unit is an integrated part of the small angle X-ray scattering instrument, making it possible to control the coating process while recording scattering measurements in situ, enabling us to follow the crystal formation during drying. By varying the distance between the coating head and the point where the X-ray beam hits the film, we obtained measurements of 4 different stages of drying. For each of those stages, the scattering from as long a foil as possible is summed together,with the distance from coating head to scattering point kept constant. The results are average crystallographic properties for the active layer coated on a 30 m long foil. With this insight into the dynamics of crystallization in a roll-coated polymer film, we find that the formation of textured and untextured crystallites seems uncorrelated, and happens at widely different rates. Untextured P3HT crystallites form later in the drying process than expected which may explain previous studies speculating that untextured crystallization depends on concentration. Textured crystallites, however, begin forming much earlier and steadily increases as the film dries, showing a development similar to other in situ studies of these materials. [ABSTRACT FROM AUTHOR]

The tandem concept involves stacking two or more cells with complementary absorption spectra in series or parallel connection, harvesting photons at the highest possible potential. It is strongly suggested that the roll-to-roll production of organic solar cells will employ the tandem concept to enhance the power conversion efficiency (PCE). However, due to the undeveloped deposition techniques, the challenges in ink formulation as well as the lack of commercially available high performance active materials, roll-to-roll fabrication of highly efficient organic tandem solar cells currently presents a major challenge. The reported high PCE values from lab-scale spin-coated devices are, of course, representative, but not helpful for commercialization. Here, organic tandem solar cells with exceptionally high fill factors and PCE values of 7.66% (on glass) and 5.56% (on flexible substrate), which are the highest values for the solution-processed tandem solar cells fabricated by a mass-production compatible coating technique under ambient conditions, are demonstrated. To predict the highest possible performance of tandem solar cells, optical simulation based on experimentally feasible values is performed. A maximum PCE of 21% is theoretically achievable for an organic tandem solar cell based on the optimized bandgaps and achieved fill factors. [ABSTRACT FROM AUTHOR]

A solution-processed silver film is employed in the processing of top-illuminated indium-tin-oxide (ITO)-free polymer solar cells in single- and double-junction (tandem) structures. The nontransparent silver film fully covers the substrate and serves as the bottom electrode whereas a PEDOT:PSS/Ag grid forms the semitransparent top electrode. All layers are roll-coated/printed on a flexible substrate by using only two techniques: slot-die coating for up to 11 consecutive layers and flexo-printing for the last Ag grid layer. The slot-die coated Ag film is compared to an evaporated Ag film in terms of surface morphological and topographical properties and to ITO in terms of flexibility. The slot-die coated Ag film demonstrates extremely low roughness (a root-mean-square roughness of 3 nm was measured over 240×320 μm2 area), is highly conductive (<1 Ω/□), highly flexible, and cost-effective in comparison to other reported metal films applied in polymer solar cells. Such properties result in high fill factors exceeding 50 % in both single and tandem structures on large-area devices (1 cm2) and the corresponding efficiencies exceed 2 %. [ABSTRACT FROM AUTHOR]

ABSTRACT Two low-band gap polymer series based on benzo[1,2- b:4,5- b′]dithiophene (BDT) and dithienylbenzothiadiazole, with different numbers of fluorine substituents on the 2,3,1-benzothiadiazole unit, have been synthesized and explored in a comparative study of the photochemical stability and operational lifetime in flexible large area roll-coated bulk heterojunction solar cells. The two polymer series have different side chains on the BDT unit, namely 2-hexyldecyloxy (BDTHDO) ( P1-P3) or 2-hexyldecylthiophene (BDTTHD) ( P4-P6). The photochemical stability clearly shows that the stability enhances along with the number of fluorine atoms incorporated on the polymer backbone. Fabrication of the polymer solar cells based on the materials was carried out in ambient atmosphere on a roll coating/printing machine employing flexible and indium-tin-oxide-free plastic substrates. Solar cells based on the P4-P6 series showed the best performance, reaching efficiencies up to 3.8% for an active area of 1 cm2, due to an enhanced current compared to P1-P3. Lifetime measurements, carried out according to international summit on OPV stability (ISOS), of encapsulated devices reveals an initial fast decay for P1-P6 in the performance followed by a much slower decay rate, still retaining 40-55% of their initial performance after 250 h of testing under ISOS-L-1 conditions. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014, 52, 893-899 [ABSTRACT FROM AUTHOR]

Printed Energy Technologies: Printing enables fast roll‐to‐roll manufacturing, which can aid an energy technology in being converted to the large scale by allowing the energy invested in the product to be reduced and significantly shortening the energy payback time. This special issue of Energy Technology brings together experts that highlight some of the key efforts in printed energy technologies, including solar cells, batteries, light‐emitting diodes, and others. [ABSTRACT FROM AUTHOR]

Scaling across orders of magnitude: The cover image illustrates how the size of equipment increases upon scaling up polymer solar cell manufacturing using coating and printing techniques from the small laboratory scale to pilot scale, as reviewed in article on page 293 from the Technical University of Denmark. The illustration applies generally to all printed energy technologies and shows how you have to transcend from hand‐sized to human‐sized, increasing the capital investment, running cost, operating cost. and risk. The chain of equipment illustrated, if used progressively by growing scale one step at a time, is an efficient means to manage risk and also to carry out the process development needed during scaling. The step from the spin coater or laboratory coater (not shown) to the microscale roll‐to‐roll coater or the mini roll coater is already very large in terms of processed area by a factor of several hundred; moving further up in scale quickly implies that one has to bridge the gap in scales by many orders of magnitude in terms of processed area per time. Once the scale is reached one is in a position where enormous output at low cost is granted and this applies to printed light emitters, printed energy storage, or printed energy harvesting; it is all in the approach. In this Special Issue on printed energy technologies, each of these topics and more are addressed among the contributions from the many of the leading groups in the field. [ABSTRACT FROM AUTHOR]

Jens W. Andreasen and co‐workers identify and surmount the challenges of fast and scalable manufacture of polymer tandem solar cells as reported in article number 1400736. This is accomplished by combining in situ X‐ray scattering and the high resolution 3D X‐ray vision provided by coherent synchrotron radiation diffractive imaging. [ABSTRACT FROM AUTHOR]

Roll with it: The cover image highlights an ambient slot–die coated Ag film onto which polymer solar cells (PSCs) are fabricated. Three different thicknesses of the same photoactive polymer are coated on the three different Ag stripes. The three stripes appear with three distinct colors due to the reflectivity of the underlying coated Ag film. Metal films bring several advantages including their reflectivity, low sheet resistance, and barrier properties. Until now, however, only evaporated metal films have been successfully utilized as electrode material in organic solar cells. In the Full Paper on page 651 ff., Frederik C. Krebs and colleagues at the Technical University of Denmark demonstrate the application of an ambient slot–die coated Ag film to roll‐processing of single‐ and tandem‐junction ITO‐free polymer solar cell devices. The slot–die coated Ag electrodes on Polyethylene terephthalate (PET) substrates are found to be superior to vapor‐deposited silver films in terms of roughness, and superior to comparable ITO films on PET in terms of flexibility. By employing only two simple roll‐to‐roll compatible processing methods in the fabrication of complete devices, including both electrodes (slot–die coating was used for up to 11 layers and flexo‐printing for the last counter electrode), large‐area single and tandem devices are demonstrated with fill factors (FF) exceeding 50 % in both types. [ABSTRACT FROM AUTHOR]

The ability of printed organic solar cells (OSCs) to survive repeated mechanical deformation is critical to large-scale implementation. This paper reports an investigation into the mechanical stability of OSCs through bending and torsion testing of whole printed modules. Two types of modules are used that differ slightly in thickness as well as on the basis of the electrode materials: silver nanowires or carbon-based inks. Each type of module is subjected to two different mechanical modes of deformation, bending and torsion, of several thousand cycles per module using a purpose-built robotic device. Analysis of the distribution of stress in the devices performed by finite-element modeling predicts the locations of failure. Failure upon bending originates at the laser-cut edges of the modules from shear at the clamp/module interface leading to crazing of the plastic barrier encapsulant foils. This crazing leads to eventual delamination due first to decohesion of the active layer at the edge of the modules and later to deadhesion between the PEDOT:PSS (electrode) and P3HT:PCBM (semiconductor) layers. The torsion mode imposes greater stresses than the bending mode and thus leads to failure at fewer strain cycles. Failure during torsion occurs through crack propagation initiated at stress concentrations on the edges of the module that were imposed by their rectangular geometry and ultimately leads to bifurcation of the entire module. Rather than the differences in electrode materials, the differences in survivability between the two types of modules are attributed mostly to the thickness of the substrate materials used, with the thinner substrate used in the carbon-based modules (~160 µm) failing at fewer strain cycles than the substrate used in the silver-nanowire-based modules (~190 µm). Taken together, the results suggest ways in which the lifetimes of devices can be extended by the layouts of modules and choices of materials. [ABSTRACT FROM AUTHOR]

The challenge of preparing cross sections of organic photovoltaics (OPV) suitable for transmission electron microscopy (TEM) and scanning TEM (STEM) is addressed. The samples were polymer solar cells fabricated using roll-to-roll (R2R) processing methods on a flexible polyethylene terephthalate (PET) substrate. Focused ion beam (FIB) and ultramicrotomy were used to prepare the cross sections. The differences between the samples prepared by ultramicrotomy and FIB are addressed, focusing on the advantages and disadvantages of each technique. The sample prepared by ultramicrotomy yielded good resolution, enabling further studies of phase separation of P3HT:PCBM by means of energy filtered TEM (EFTEM). The sample prepared by FIB shows good structure preservation, but reduced resolution due to non-optimal thicknesses achieved after treatment. Degradation studies of samples prepared by ultramicrotomy are further discussed, which reveal particular effects of the ISOS-L-3 aging test (85 °C, 50% R.H., 0.7 Sun) onto the sample, especially pronounced in the silver layer. [ABSTRACT FROM AUTHOR]

We investigated the response of roll coated organic solar cells at different bias voltages and illumination levels to implement a detailed impedance model. The technique used for the investigation is based on the combination of standard DC characterization with the impedance spectroscopy at different bias and illumination intensity conditions. We analyzed both fresh and intentionally degraded cells. The impedance spectra show different peaks evolutions, depending on the degradation of the cells. Moreover, the same trend appears by measuring the cell at different illumination levels. To describe the cell impedance behaviors we suggest an electrical model based on distributed elements. By fitting the model to experimental data, we extrapolate the parameters related to electron transport, recombination and accumulation. The main differences between fresh and degraded samples are underlined. [ABSTRACT FROM AUTHOR]

The practical design of a wirelessly controlled portable IV-curve tracer based on a capacitive load is described. The design is optimized for the measurement of solar cell modules presenting a high open circuit voltage of up to 6 kV and a low short circuit current below 100 mA. The portable IV-tracer allows for on-site/in-situ characterization of large modules under real operating conditions and enables fast detection of potential failure of anomalies in electrical behavior. Currently available electronic loads only handle voltages up to around 1 kV. To overcome cost and safety issues related to high voltage applications, the design is based on low cost components, battery-based isolated supply and wireless communication. A prototype has been implemented and field tested for characterization of different organic photovoltaic modules (OPV) made according to the infinity concept with a large number of serially connected single junctions (~7.450 single junctions) presenting open circuit voltages up to 5.6 kV. [ABSTRACT FROM AUTHOR]

This paper presents a field-trial of organic photovoltaic (OPV) technology used within a practical application for rural electrification in Rwanda. Fourteen, large area, flexible, ITO-free, roll-to-roll processed OPV modules, encapsulated with low-cost materials, were installed on corrugated steel roofs at two sites in a rural village in Southern Rwanda and subject to continuous monitoring. This field-trial exposed modules to very high levels of insolation, in particular in the UV, high temperatures and heavy rainfall. Results show that the modules exhibit practical lifetimes (to degrade by 20% of their initial capacity) of between 2½ and 5 months, a value 5–6 times lower than control modules kept both in the dark and outdoors in Roskilde, Denmark. Degradation was primarily the result of extensive delamination caused by failure of the non-UV stable encapsulation, which led to decay in the FF, V oc and I sc of the module. [ABSTRACT FROM AUTHOR]

We present a study of the rate-limiting spin-dependent charge-transfer processes in different polymer/fullerene bulk-heterojunction solar cells at 10 K. Observing central spin-locking signals in pulsed electrically detected magnetic resonance and an inversion of Rabi oscillations in multifrequency electron-double-resonance spectroscopy, we find that the spin response of both spin-coated and printed P3HT/PCBM and spin-coated PCDTBT/PCBM solar cells at low temperatures is governed by bipolar polaron pair recombination and quantitatively determine the polaron-polaron coupling strength with double electron-electron resonance experiments. Furthermore spin Hahn echo decay and inversion recovery measurements are performed to measure spin coherence and recombination times of the polaron pairs, respectively. [ABSTRACT FROM AUTHOR]

We report manufacture of fully printed and coated polymer solar cells on a small scale roll-to-roll coater representing the intermediate scale between laboratory and pilot scale. We highlight the enormous span in scale between the laboratory scale and the intended industrial scale by a factor of >100.000 and detail how this enormous scale must be covered by equipment that follow the scale. Especially the intermediate scale between equipment that can fit inside a fume cupboard and the typical pilot equipment with a footprint having the size of a large room presents a challenge that comprises some of the most critical steps in the scaling process. We describe the development of such a machine that comprise web guiding, tension control and surface treatment in a compact desk size that is easily moved around and also detail the development of a small cassette based flexographic unit for back electrode printing that is parsimonious in terms of ink usage and more gentle than laboratory scale flexo units where the foil transport is either driven by the flexo unit or the flexo unit is driven by the foil transport. We demonstrate fully operational flexible polymer solar cell manufacture using this new roll and roll-to-roll (R3) approach and compare with the existing methods. [ABSTRACT FROM AUTHOR]

In this study, a method to opto-electronically probe the individual junctions and carrier transport across interfaces in fully printed and coated tandem polymer solar cells is described, enabling the identification of efficiency limiting printing/coating defects. The methods used are light beam induced current (LBIC) mapping, External quantum efficiency (EQE) measurements, and monochromatic current–voltage ( I – V ) characterization. Using these methods, inherent limitations to the accuracy of EQE and LBIC measurements on non-ideal tandem solar cells are identified and described through the use of a small-signal electrical model. The model is able to predict the EQE spectrum of the non-ideal polymer tandem solar cell, using extracted values of shunt- and series resistance of the individual junction of the tandem cell. This finally enables LBIC mapping of the individual junctions of the tandem polymer solar cells, using a combination of light and voltage-biasing. [ABSTRACT FROM AUTHOR]

We present a life cycle analysis (LCA) and an environmental impact analysis (EIA) of lead based perovskite solar cells prepared according to the two most successfully reported literature methods that comprise either vapour phase deposition or solution phase deposition. We have developed the inventory for all the components employed for the two different device architectures that resemble respectively a traditional dye sensitised solar cell (DSSC) and an inverted polymer solar cell (OPV). We analyse the impacts from generation of 1 kWh of electricity and assume a lifetime of 1 year in the analysis and further present a sensitivity analysis with the operational lifetime as a basis. We find that the major impact comes from the preparation of the perovskite absorber layer due to the electrical energy required in the manufacture and also make the striking observation that the impact of toxic lead(II)halides is very limited compared to methylammoniumhalides employed. This applies during the raw materials extraction, synthesis of the starting materials and manufacture of the perovskite solar cells and from these points of view the lead based perovskite solar cells do not pose extra concerns when compared to contending solar cell technologies in the cradle-to-gate scenario considered here. The environmental impact of the perovskite solar cells in the operational phase and the decommissioning phase representing a cradle-to-grave analysis is not currently possible and will have to await large scale outdoor demonstration where emission to the environment during the operation and decommissioning phase can be measured. The main conclusion is that in the cradle-to-gate analysis there are no compelling reasons to dismiss lead based perovskites as a solar cell technology. [ABSTRACT FROM AUTHOR]

A novel cross-linkable azide-functionalized diketopyrrolopyrrole based compound DPP(BT-N3)2 was designed and synthesized via Stille coupling. Cross-linking of such molecule could help us fabricate insoluble film which could be used to fabricate heterostructures through solution processing, without dissolving the pre-patterned layers. In order to investigate the photovoltaic performances of the newly synthesized compound, large area solar cells were produced by roll coating technique. Two set of devices were fabricated by employing DPP(BT-N3)2 as either an electron donor or acceptor. A best power conversion efficiency of 0.067%, combined with an open circuit voltage of 0.53 V, and a fill factor of 37.6% were obtained for the device with DPP(BT-N3)2 as an electron acceptor. In addition, we could prove that the large area small molecule based organic solar cells could be fabricated using roll coating, which could be used in the industries for large-scale of production. [ABSTRACT FROM AUTHOR]