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Improving the performance of solar modules requires the implementation of both spectral and directional irradiance optimization. The performance of bifacial four-terminal tandem minimodules with a 100 cm2 area is reported, both indoor and outdoor measurements. We demonstrate a 24.5 mW/cm2 (bifacial irradiance 200 W/m2) bifacial tandem power density, measured according to a tandem adapted IEC60904-1-2 protocol, which constitutes a 3 mW/cm2 gain with respect to monofacial use. In addition, we show that in outdoor measurements bifacial four terminal tandems outperform identical monofacial four terminal tandems by 26% on average, depending on incident angle, injection level and temperature, in a 10% albedo environment. The average gain is higher for outdoor performance than for indoor performance, due to variations in relative rear irradiance.

4-terminal tandem technology is a straightforward approach to bring to the market perovskite/crystalline silicon tandem modules. However, dealing with 4 terminals poses a challenge at system level for practical deployment. We have produced large area 4-terminal perovskite/crystalline silicon tandem modules for a study of the performance of a 2-terminal voltage matched (2T VM) configuration versus an unconstrained 4-terminal (4T) configuration. The 2T VM configuration is a very interesting proposition to deal in practice with 4 terminal tandem technology at module level. The tandem module assembly consisted of 3 perovskite submodules of 31 cells and 100 cm2 aperture area each, and 3 c-Si submodules of 16 cells and 100 cm2 aperture area each. We have varied the voltage-mismatch from 13% to 42%, by varying the electrically connected c-Si string length. The resulting power loss for 2T VM relative to 4T varied between 4.5% and 20%. We have focused on combining one perovskite submodule with the series connection of the three silicon submodules, using the other two perovskite submodules as optical filter only. We find that the 2T VM power output follows roughly the expected values calculated from the individual characteristics, however, with a 2-3% additional power loss. Analysis of this additional power loss will require precise monitoring of time dependence of I-V characteristics, transmission of the submodules, and other relevant parameters.

Scalable sheet-to-sheet slot die coating processes have been demonstrated for perovskite solar cells and modules. The processes have been developed on 6 in. × 6 in. glass/ITO substrates for two functional layers: the perovskite photo-active layer and the Spiro-OMeTAD hole transport layer. Perovskite solar cells produced using these slot die coating processes demonstrate device performances identical to the spin coated devices. All manufactured devices illustrate a high level of reproducibility. The developed slot die coating processes were also used for the manufacturing of perovskite PV modules. Large area modules of 12.5 × 13.5 cm2 were realized by slot die coating on 6 in. × 6 in. substrates in combination with newly developed laser ablation processes for conventional P1-P2-P3 monolithic cell interconnections. The modules demonstrate power conversion efficiencies above 10%, with a power output of 1.7 W. This achievement is an important milestone in the development of up-scalable manufacturing technologies for perovskite PV modules.

This paper reports on the analysis and comparison of mechanical and laser patterning in the fabrication of perovskite thin-film photovoltaic modules. Besides stability, device upscaling and module fabrication is a key challenge for the commercialization of perovskite photovoltaics. Here, the focus is on the optimization of the P2 interconnection that represents the electrical connection between serially connected cells in a module. The specific contact resistivity for P2 interconnection is determined by using an enhanced transmission line method. Mechanical or laser patterning are used to fabricate 4 cm $^{2}$ modules with aperture area efficiencies of up to 15.3% and geometrical fill factors as high as 94%. With the application of a simulation program with an integrated circuit emphasis-based electrical device model, the interconnection losses are quantified, and optimal designs for perovskite modules are presented.

In order to commercialize the perovskite solar cells (PSC) technology, efficient and industrial deposition methods over large areas have to be adopted, and the device architectures have to provide long term stability. In this work we combine several upscalable deposition methods to develop a stable semitransparent PSC. The control of the uniformity of perovskite crystallization by tailoring the ink formulation and the drying process was pursued in order to drastically reduce the efficiency losses over an area increase of 3 orders of magnitude (from 0.04 to 100 cm2). When adopting sputtered ITO as top electrode, the stack retains up to 90% of the initial performance after 1000hrs at 85 °C. The use of laser patterning to define P1 P2 and P3 scribes for series interconnected modules enables the fabrication of thermally stable minimodule (4cm2) and large module (100cm2). Finally an outlook on the use of the perovskite device as top cell in a 4T tandem architecture with commercial c-Si cells will be provided.

In this work, efficient rigid and flexible semi-transparent perovskite solar cells (ST-PSCs) were prepared in inverted (light incidence through hole transport layer) configuration. All layers were deposited by a combination of low-temperature solution-based, sputtering and spatial atomic layer deposition (sALD) techniques, which can be potentially up-scalable for sheet to sheet and roll to roll manufacturing lines. The rigid and flexible opaque PSCs reach stabilized power conversion efficiency (PCE) of 19% and 16% [1], while rigid ST-PSC reaches 16.4% stabilized PCE. Besides those results, we have developed our current flexible opaque stack to the flexible semi-transparent stack using top TCO electrode and sALD buffer layer. We also highlight that the inverted configuration exhibited extremely high infrared transparency [2] and a remarkable stability during the light and thermal stress. The encapsulated ST-PSCs retained 93% of their initial stabilized PCE after 3000h aging at 85°C in a nitrogen atmosphere. Interestingly, using highly transparent transport layers, rigid and flexible ST-PSCs show comparable efficiency by illumination from both rear and front TCO sides, resulting in a bifacility of 99%.

The industrialization of perovskite solar cells (PSC) require processes to efficiently deposit the constituent layers over large areas. In this work we optimized the use of slot die coating process for both sheet-to-sheet (S2S) and roll-to-roll (R2R) manufacturing. Particular focus have been put on the control of the uniformity of perovskite crystallization by tailoring the ink formulation and the drying process in order to avoid any efficiency losses over an area increase of 3 orders of magnitude (from 0.09 to 144 cm2). In this way we were able to fabricate 144 cm2 modules with 13.8% stabilized efficiency on aperture area on glass (14.5% on active area). At the same time, by developing the R2R slot die deposition process of the perovskite layer, we demonstrated 160 cm2 flexible module with 10.1 % stabilized efficiency on aperture area (11.0% on active area). In addition, fully R2R coated cells exhibit up to 16% efficiency. An outlook on how to upscale more stable perovskite cells (i.e. with pin structure) will be given. These results prove how to optimize the upscaling process towards large area manufacturing of perovskite solar modules on both rigid and flexible substrate.

© 2018 The Royal Society of Chemistry. Thin film perovskite photovoltaic devices combine high power conversion efficiencies with low weight, large area, high speed production capabilities and high versatility in form factor. With this paper, an additional feature is added to the device property portfolio: optical transparency. Results on translucent perovskite modules with selectively tuned levels of transparency are reported by applying the industrially established fabrication process of partial area ablation to high efficiency opaque devices. After process completion, the final devices consist of opaque areas that absorb the light, and transparent areas that permit neutral light transmission. We compare the effectiveness of using two active area removal techniques: mechanical scribing and laser ablation, and determine the factors that limit the maximum transparency and power conversion efficiency. Moreover, we show how the choice of the ablation method and design of the active area removal pattern affect and limit the maximum light utilization efficiency ratio that can be achieved with this fabrication process. The resulting 4 cm2 translucent modules cover a range of visible light transparency from 7 to 37% with a corresponding power conversion efficiency of 5 to 13%. ispartof: JOURNAL OF MATERIALS CHEMISTRY C vol:6 issue:12 pages:3034-3041 status: published

Flexible semi-transparent organic photovoltaic (OPV) modules were manufactured by roll-to-roll slot–die coating of three functional layers [ZnO, photoactive layer, and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS)] and either the screen printing or inkjet printing of the top electrodes. A poly(3-hexylthiophene):[6,6] phenyl C61-butyric acid methyl ester (P3HT:PCBM) layer deposited from non-chlorinated solvents was used as the absorber layer. The modules were realized by slot–die coating of the layers onto a laser-patterned polyethylene terephthalate/indium-tin oxide (PET/ITO) substrate, followed by laser structuring of all coated layers. The top electrodes were realized by high-resolution printing, which, combined with laser patterning of other layers, enables manufacturing of the modules with high geometrical fill factor (92.5%). The modules have an active area of 156 cm2, and contain 13 serially interconnected cells. Two semitransparent electrodes (ITO from the bottom and PEDOT:PSS/Ag-grid from the top side) allow the absorption of photons incident from both sides. The performance of the modules was evaluated and compared among the modules by considering the following factors: (i) roll-to-roll slot–die coated vs. spin-coated layers,(ii) inkjet-printed vs. screen-printed top electrodes, (iii) top vs. bottom illumination. The demonstrated technology is one of the proven feasible ways towards industrial manufacturing of the OPV modules.

The proper long term operation of organic electronic devices like organic photovoltaics OPV depends on their resistance to environmental influences such as permeation of water vapor. Major efforts are spent to encapsulate OPV. State of the art is sandwich-like encapsulation between two ultra-barrier foils. Sandwich encapsulation faces two major disadvantages: high costs (∼1/3 of total costs) and parasitic intrinsic water (sponge effects of the substrate foil). To fight these drawbacks, a promising approach is to use the OPV substrate itself as barrier by integration of an ultra-barrier coating, followed by alternating deposition and structuring of OPV functional layers. In effect, more functionality will be integrated into less material, and production steps are reduced in number. All processing steps must not influence the underneath barrier functionality, while all electrical functionalities must be maintained. As most reasonable structuring tool, short and ultrashort pulsed lasers USP are used. Laser machining applies to three layers: bottom electrode made of transparent conductive materials (P1), organic photovoltaic operative stack (P2) and top electrode (P3). In this paper, the machining of functional ∼110...250 nm layers of flexible OPV by USP laser systems is presented. Main focus is on structuring without damaging the underneath ultra-barrier layer. The close-to-process machining quality characterization is performed with the analysis tool "hyperspectral imaging" (HSI), which is checked crosswise with the "gold standard" Ca-test. It is shown, that both laser machining and quality controlling, are well suitable for R2R production of OPV.

We present the development of laser processes for flexible OPV on roll-to-roll (RR2R) produced thin film barrier with indium tin oxide (ITO) as transparent conductive (TC) bottom electrode. Direct laser structuring of ITO on such barrier films (so-called P1 process) is very challenging since the layers are all transparent, a complete electrical isolation is required, and the laser process should not influence the barrier performance underneath the scribes. Based on the optical properties off the SiN and ITTO, ultra-short pulse lasers inn picosecond and femtosecond regime with standard infrared (IR) wavelength as well as lasers with new a wavelength (22 μm regime) are tested for this purpose. To determine a process window for a specific laser a fixed methodology is adopted. Single pulse ablation tests were followed by scribing experiments where the pulse overlap was tuned by varying laser pulse fluence, writing speed and frequency. To verify that the laser scribing does not result inn barrier damage underneath, a new test method was developed based on the optical Ca-test. This method shows a clear improvement in damage analysis underneath laser scribes over normal optical inspection methods (e.g. microscope, optical profiler, SEM). This way clear process windows can be obtained for IR TC patterning. © (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

Organometallic halide perovskite solar cells (PSCs) are extremely promising novel materials for thin-film photovoltaics, exhibiting efficiencies over 22% on glass and over 17% on foil 1, 2. First, a sheet-to-sheet (S2S) production of PSCs and modules on 152x152 mm2 substrates was established, using a combination of sputtering, e-beam evaporation, slot die coating and thermal evaporation (average PCE of 14.6 ± 1.3 % over 64 devices, more than 10% initial PCE on modules). Later the steps towards a roll-to-roll production will be investigated, starting from the optimization of the stack to make it compatible with a faster production at low temperature. A water based SnOx nanoparticles dispersion was used as solution processable ETL, and the deposition process was scaled-up from spin coating to R2R slot die coating on a 300 mm wide roll of PET/ITO. R2R production is often carried out in ambient atmosphere and involve the use of large volumes of materials, thus a first point is the development of a green solvent and precursor system for the perovskite layer to prevent the emission of toxic compound in the environment. The first results on device fabrication are encouraging, which allow partial R2R manufacturing of flexible PSC (R2R coating of SnOx and perovskite, S2S for Spiro-OMeTAD and gold) with stabilized PCE of 12.6%, a remarkable value for these novel devices. This result can be considered an important milestone towards the production of efficient, low cost, lightweight, flexible PSC on large area.

Local laser ablation of the cathode of OLEDs has been applied to create a population of pinholes of the same size. This enables the direct comparison at different conditions of black spots and grey spots in the emission of OLEDs as a result of water ingress into the device. We confirmed earlier observations on the operational effect of black spot growth as determined in a sequential test on particle induced pinholes. Furthermore, we measured the operational effect in parallel, providing data that are test independent. With the same population of pinholes we studied the operational effect of grey spot growth. The observed larger operational effect of grey spot growth with respect to that of black spot growth is attributed to a lateral flow of protons to the centre of the black spot. In this part of the black spot a depletion region is present which is created by transport of H3O+ to the cathode under the influence of the applied electric field. This proposal is supported by the observation of black and grey spot growth in polymer LEDs on basis of PEDOT:PSS with increased pH.

To protect organic flexible devices from the ambient, they have to be encapsulated. Depending on the application in mind (OLED lighting, PV) different thin-film encapsulation methodology can be chosen. Each encapsulation process has different requirements and fabrication process freedom might be restricted, for example by mechanical reliability requirements or the total cost of the end product. Here we will show our recent investigations into different thin-film barriers with respect to their application and the route to production.

This paper presents a study of selective ablation of thin organic films (LEP- Light Emitting Polymer, PEDOT:PSS- Poly 3,4-ethylenedioxythiophene: polystyrene sulfonate) by using 248 nm Excimer laser, on various kinds of multilayered SiN barrier foils for the development of Organic Light Emitting Diodes (OLED). Different Silicon Nitride (SiN) barrier foils with dedicated absorption spectra are taken into account for this purpose. The drive for looking into different types of SiN originates from the fact that the laser selective removal of a polymer without damage to the barrier layer underneath is challenging in the dynamic laser processing of thin films. The barrier is solely responsible for the proper encapsulation of the OLED stack. The main limitation of current OLED design is its shorter life span, which is directly related to the moisture or water permeation into the stack, leading to black spots. An optimization of laser parameters like fluence and number of shots has been carried out for the various types of SiN barrier foils. We are able to obtain a wider working process window for the selective removal of LEP and PEDOT:PSS from SiN barrier, by variation of the different types of SiN.

Reliable interconnection technology is key to the realization of reliable hybrid microelectronic systems that combine printed electronics and silicon technology. Flexible hybrid electronic systems-in-foil (SiF) that are typically suited for roll-to-roll (R2R) manufacturing place additional requirements and demands on interconnects. In this paper, three novel interconnection methodologies for SiF are compared for a novel face-up integration approach for ultra-thin chip on foil. Laser scribing, inkjet printing and laser-induced forward transfer (LIFT) are the technologies compared with each other, as well as with electroplating, a standard technology widely used in the electronics industry. The comparison is based on experimental investigation into via filling, interconnect deposition, electrical conductivity and interconnect reliability. The selection of an interconnection technology for practical implementation is the key outcome of this paper. © 2012 IEEE.

The placement and integration of ultra-thin chips (UTCs) on low-cost polymer foils is a key challenge in the realization of large-area flexible electronic products. Such products, are for cost reasons, preferably fabricated on low cost polyester foils like PET/PEN. A disadvantage of these materials is that they have a low thermal stability. As a consequence of this, the majority of existing chip integration technologies cannot be used. A novel approach for placement and interconnection of UTCs is presented in this paper. This approach, which involves face-up bonding of UTC and its subsequent interconnection, is compatible with low-cost polymer foils. The key process steps involved in UTC integration using the proposed methodology are discussed in detail. The fabrication of a technology demonstrator to validate the proposed concept is also detailed.

A study on via drilling and channel scribing on PEN and PET substrates for flexible electronic application is discussed in this paper. For the experiments, both KIF excimer laser (248 nm) and frequency tripled Nd:YAG (355 nm) laser are used. Different measurement techniques like optical microscopy, Dektak profilometer, Confocal microscopy and scanning electron microscopy (SEM) were employed to characterize the quality of the channels and vias. The patterned structures were filled by three different methods using a conductive paste or ink that is cured in an oven at an elevated temperature. The cross-sectional measurements of channels and vias were carried out using SEM to study the uniformity of filling.

The fast-growing market of organic electronics stimulates the development of versatile technologies for structuring thin-film materials. Ultraviolet lasers have proven their full potential for patterning organic thin films, but only a few studies report on interaction with thin-film barrier layers. In this paper, we present an approach in which the laser patterning process is optimized together with the barrier film, leading to a highly selective patterning technology without introducing barrier damage. This optimization is crucial, as the barrier damage would lead to moisture and oxygen ingress, with accelerated device degradation as a result. Following process optimization, a laser processed flexible organic LED has been fabricated and thin-film encapsulated and its operation is shown for the first time in atmospheric conditions.

A new technique is presented for low-energy X-ray fluorescence micro-distribution analysis of low-Z elements at micrometer spatial resolutions. The technique is based on the use of a laser plasma X-ray source and spherically curved multilayer optics. A large collimator is used to focus the light from the laser plasma on the sample and a Schwarzschild mirror set is used to image the fluorescent radiation on a 2D CCD unit. A first system, now under development, is designed for detection of the carbon K alpha-line. The system consists of a Cr/Sc collimator of 260 mm diameter, focusing 0.7 sr of the light from the plasma on the sample, and an Fe/C Schwarzschild mirror set with 20 x magnification for detection of the carbon in the sample. A resolution in the micrometer range is expected to be achievable, with a detection limit of a few per cent. Upgrading of this system is expected to result in sub-micrometer resolution and a detection limit in the ppm range.

A femtosecond laser has been successfully utilized for patterning thin Flexible Organic Light Emitting Diode (FOLED) structures of individual layer thickness around 100nm. The authors report in this paper a step-like ablation behavior at the layer interfaces which accounts for a local removal of entire layers. Various surface analyzing techniques are used to investigate the morphologies and chemical compositions within and in the vicinity of the ablation areas. This study opens a new avenue in selectively ablating different layers from a multilayer stack on flexible substrates using fs lasers allowing post deposition structuring of large area flexible organic electronic devices. (C)2010 Optical Society of America