High Q femtoREGEN TM UC laser systems for industrial microprocessing applications

Progress in Photovoltaics

Stubhan

et al. 2013

In this paper, we demonstrate that laser patterning of organic solar cells by ultrafast laser systems (pulse length <350 fs) is an attractive process to produce photovoltaic modules with outstanding high geometric fill factors. Moreover, in terms of precision, registration, and debris generation and in terms of keeping the damage to the underneath layers at a minimum, ultrafast laser patterning with a pulse length of few hundreds of femtoseconds turns out to yield superior results. Ablation of all three different solar cell layers (electrodes (P1 and P3) and interfaces and semiconductor (P2)) is achieved with a single wavelength simply by a precise adjustment of the laser fluence and the patterning overlap. Camera positioning allows a precise registration between the various processing steps and a reduction of the width of the overall interconnection regime to the hundreds of micrometers dimension, resulting in high geometrical fill factors of over 90% for monolithically interconnected organic solar cell modules.

Section: Introductionmentioning

confidence: 98%

Patterning of organic photovoltaic modules by ultrafast laser

Progress in Photovoltaics

Stubhan

et al. 2013

All sub‐nanosecond laser monolithic interconnection of OPV modules

Progress in Photovoltaics

Winter

Gavrilova

et al. 2019

Although green femtosecond lasers provide outstanding quality and wide processing windows for monolithic interconnection of the individual cells in organic photovoltaic (OPV) modules, they are hardly used in commercial applications, due to cost reasons.In this work, a process has been developed that allows the monolithic interconnection in OPV modules with an infrared sub-nanosecond laser exclusively, without compromising the performance of the modules. While the photoactive layer is removed easily by green femtosecond pulses without damaging the bottom electrode, this is not possible for infrared nanosecond pulses, due to their much larger optical penetration length, which significantly exceeds the thickness of the active layer and is well absorbed by the indium tin oxide (ITO) layer. This leads to damage of the ITO bottom electrode, which in turn compromises the functionality of the module.By systematically varying single-pulse laser fluence and spatial pulse overlap, the laser parameters are optimized in such a way that the contact area between the residues of the metal oxide bottom electrode and the silver nanowire top electrode is maximized so that the electrical resistances of the contacts are sufficiently small not to affect device performance. This is demonstrated by presenting large-area OPV modules based on the well-characterized reference system P3HT:PCBM that show efficiencies of up to 2.4%. This achievement opens up the way towards reliable roll-to-roll (R2R) laser patterning processes with sub-nanosecond lasers and thus represents a breakthrough with respect to cost-effective R2R manufacturing of OPV modules, due to grossly reduced investment and maintenance costs for laser sources. KEYWORDS flexible organic photovoltaic module, laser patterning, sub-nanosecond pulses 1 | INTRODUCTION Besides flexibility, lightweight, semitransparency, and customized color and shape, the attractiveness of polymer-based organic photovoltaics (OPVs) is based on the possibility of cost-effective deposition of the modules from the liquid phase on large areas by roll-to-roll (R2R) processes. 1 In order to avoid resistive losses and to provide useful voltages, the modules are divided into several cells, which are serially interconnected. The area needed for interconnection is inactive for PV energy generation and is therefore named dead area. The geometrical fill factor (GFF) is defined by the ratio of the PV active area and the total module area and enters directly the calculation of the module efficiency. Traditionally, the interconnection of individual cells is achieved by printing a bottom electrode, the photoactive layer,

Flexible organic tandem solar modules with 6% efficiency: combining roll-to-roll compatible processing with high geometric fill factors

Spyropoulos

et al. 2014

Energy Environ. Sci.

Self Cite

Organic solar cell technology bears the potential for high photovoltaic performance combined with truly low-cost, high-volume processing.Here we demonstrate organic tandem solar modules on flexible substrates fabricated by fully roll-to-roll compatible processing at temperatures <70 C. By using ultrafast laser patterning we considerably reduced the "dead area" of the modules and achieved geometric fill factors beyond 90%. The modules revealed very low interconnection-resistance compared to the single tandem cells and exhibited a power conversion efficiency of up to 5.7%. Bending tests performed on the modules suggest high mechanical resilience for this type of device. Our findings inform concrete steps towards high efficiency photovoltaic applications on curved, foldable and moving surfaces.