area of large area perovskite solar cells and modules by using sheet-to-sheet (S2S) techniques. [10][11][12][13][14] Blade coating is often employed as a scalable method for the manufacturing of PSC and has demonstrated PCE values of 19-20% on cell level [15,16] and PCE values of 15.3% and 14.6% for modules with aperture areas of 33.0 and 57.2 cm 2 , respectively. [16] Monolithic perovskite modules with an active area of 70 cm² and with a PCE of 10.74% were fabricated using scalable printing processes. [12] S2S slot die coated solar cells on a glass substrate with the efficiency of 11.96% were demonstrated by Hwang et al. [11] and 5 × 5 cm 2 modules with PCE of 10.6% were demonstrated by Cai et al. [17] Slot-die coated perovskite-based photovoltaic (PV) modules of 168 cm 2 with a PCE of 10% [18,19] and later the modules of 144 cm 2 with a PCE of 14.5% were in a recent press release of Solliance. [20] In order to allow the manufacturing of flexible PSCs for future high-volume production, roll-to-roll (R2R) processing technologies need to be developed. [21,22] First attempts of R2R manufacturing have been demonstrated already by some research groups. [23][24][25][26][27] A mini slot die coater built on a 3D printing platform allowed the manufacturing of flexible perovskite solar cells with up to 11.0% PCE. [25] A blowing-assisted drop-casting on flexible R2R moving substrates results in perovskite solar cells with PCE of up to 11.16%. [26] However, future mass production of the perovskite solar cells requires the development of industry compatible large area deposition methods. The technology for R2R deposition of PSC requires optimization of several parameters simultaneously, namely: 1) proper solvent choice (viscosity, boiling point, toxicity, price, etc.); 2) fast crystallization kinetics (required by the high speed of the R2R deposition) preferably in ambient atmosphere; 3) layer uniformity over the large area; 4) PCE of the devices, etc. Hence, a dedicated optimization of the R2R drying and annealing conditions, which heavily contribute to the abovementioned issues, will be needed. The current study is the first successful example of large area R2R manufacturing of PSC in ambient condition using nontoxic solvents. The developed processes are compatible with industrial manufacturing on a plastic substrate. The stabilized efficiencies of the manufactured devices reached the record value of 13.5%. Using prototype industrial processes and equipment with optimized in-line R2R coating, drying, and annealing, the results of this study will help in bringing the PSC technology one step closer to future commercialization.The feasibility of upscaling the perovskite solar cells technologies to high volume production using roll-to-roll (R2R) slot die coating is demonstrated in this study. Perovskite solar cells are produced by R2R slot die coating on flexible substrates with a width of 30 cm and the web speed of 3-5 m min −1 . R2R deposition of the electron transport layer and perovskite is performed at ambient atmospher...

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 crosssectional areas have been investigated. The effect of the width and height of the grid lines and busbars has been measured and modeled by direct current (DC) simulations. The electrical potential in devices with different grid profiles have been calculated and reveal critical bottlenecks in the grid electrode geometry, as the ability of the busbar to collect all the current. Experimentally, the upper limit of the conductivity of the ink-jet printed current collecting grids is limited by the topology of the grids and shadow losses in the solar cells.

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 identification of the most rational grid structure is presented. Both optical and light beam induced current (LBIC) mapping of the devices are used to support the power loss model and to follow the evolution of the performance over time. Current generation is found to be evenly distributed over the active area initially progressing to a larger graduation in areas with different performance. Over time coating defects also become much more apparent in the LBIC images. Results and DiscussionA series of large area (2 cm × 2 cm) ITO-free organic solar cell devices were prepared on glass substrates (Figure 1). The devices contained current collecting grids/high conductivity PEDOT:PSS/P3HT:PCBM/LiF:Al. A schematic illustration of the devices is shown in Figure 1a. Current collecting grids are represented as parallel lines with different spacing (pitch size) ( Figure 1b). The devices with pitch sizes of 20, 10, 6.7, 5, 3.3, 2.5, 2, and 1 mm were prepared. The pitch size is defined as the distance between the centers of two neighboring grid lines. The number of the grid lines in the devices was changed as 1, 2, 3, 4, 6, 8, 10, and 20, respectively. The width of the grid lines was constant for each batch of devices. Thus shadowing losses increase with the number of grid lines. The effect of different pitch for the grid fingers was calculated at Fraunhofer ISE using a one dimensional numerical model developed by Glatthaar et al. [37,38] Each infinitesimal cell element with width dx delivers the current j(V(x))dx. The function j(V) is given by the current-voltage (JV)-curve of a small area device. Starting from x = 0 the current sums up to I(x) (Equation 1). This current leads to a voltage drop in the current collecting electrode corresponding to Ohm´s law (Equation 2), with ρ being the sheet resistance of the electrode(s). As the current output from the infinitesimal cell elements depends on the voltage V(x) at position x, also the current density j(V(x)) depends on the position x. Therefore the two differential Equations 1 and 2 are coupled:with the boundary conditions V (x = 0) = V 0 and I(x = 0) = 0.The area loss, which in a one dimensional model is the length l loss due to coverage with grid fingers or dead area due to series circuitry is accounted for by integrating the current I from 0 to the length of the active area l active but normalizing the current to the length including the lost "area" l active + l loss . The JV curve of the grid cell or module respectively therefore is given by:The model was used to consecutively calculate the ohmic and area losses in the PEDOT layer and metal fingers. The procedure was to first calculate the loss due to the distributed PEDOT resistance and only the shadow loss induced...

Perovskite solar cells attract a lot attention as alternative energy sources for the future energy market. With the remarkable lab-scale achievements, the investigations into a high-throughput large-scale production of perovskite devices are now on the agenda. The first step towards mass manufacturing should be a replacement of toxic solvents used in the manufacturing of perovskite layer. In this study, a non-toxic and up-scaling compatible solvent system is developed. The impact of the solvent properties on the perovskite crystallization kinetics has been systematically investigated, which is found to be crucial in controlling the surface coverage and layer crystallinity. By optimizing the processing conditions, a stabilized efficiency of 16.0% is achieved with the developed non-toxic solvent system.

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