Florian Mathies

Multipass inkjet printed planar methylammonium lead iodide perovskite solar cells

We report the fabrication and optimization of multipass inkjet-printed perovskite solar cells. The presented process allows excellent control of crystallization dynamics and thickness of the perovskite layer. In order to obtain a homogenous perovskite film of large and densely packed crystals on a planar TiO2 electron transport layer we make use of an additional vacuum annealing step. Its beneficial impact was characterized in terms of device performance and laser beam induced current mapping as well as atomic force microscopy. The optimized fabrication methods resulted in power conversion efficiencies up to 11.3% of multipass inkjet printed perovskite solar cells. The spin coated reference devices reached 12.8% power conversion efficiency. With these first results, we advance the field of digital printing techniques for perovskites and demonstrate a major step towards highly efficient, low-cost and less Pb-waste producing perovskite solar cells.

Inkjet-printed perovskite distributed feedback lasers

We report on digitally printed distributed feedback lasers on flexible polyethylene terephthalate substrates based on methylammonium lead iodide perovskite gain material. The perovskite lasers are printed with a digital drop-on-demand inkjet printer, providing full freedom in the shape and design of the gain layer. We show that adjusting the perovskite ink increases the potential processing window and decreases the surface roughness of the active layer to less than 7 nm, which is essential for low lasing thresholds. Prototype inkjet-printed perovskite lasers processed on top of nanopatterned rigid as well as flexible substrates are demonstrated. Optimized perovskite gain layers printed on PET substrates demonstrated lasing and showed a linewidth of 0.4 nm and a lasing threshold of 270 kW/cm2. In addition, printing of a distinct shape shows a high level of uniformity, demonstrated by a low spatial resolved full width half maximum variation over the whole printing area. These results reveal the possibilities of digital printed perovskite layers towards large-scale and low-cost laser applications of arbitrary shape.

Inkjet Printed Perovskite Photovoltaics

In this contribution, we report on our recent advances on non-contact inkjet-printed perovskite photovoltaics. Digital inkjet printing offers rapid deposition of perovskite absorber layers for large area perovskite absorber layers as well as perovskite solar cells of arbitrary shape. By adjusting the drop spacing of the inkjet printer cartridge, we demonstrate excellent control of the perovskite layer formation and perovskite layer thickness. Our digitally inkjet-printed triple cation perovskite solar cells with 10% cesium in a mixed formamidinium/ methylammonium lead iodide/bromide composite reach initial efficiencies as high as 14.0%. Moreover, a continuous power output at constant voltage, resulting in a power conversion efficiency of 12.9% is demonstrated, representing a major improvement from previously reported results.

Scalable and low cost fabrication methods for wavelength tunable solution processed perovskite distributed feedback lasers

There is a growing interest in the use of metal halide perovskites with different compositions as highly efficient light emitters among the whole visible spectral region [1]. Several groups have observed amplified spontaneous (ASE) emission in thin perovskite films. The gain and threshold values for ASE are very promising, motivating the current effort to develop practical devices that lase.

Multipass inkjet printing of methylammonium lead iodide for planar perovskite solar cells(Conference Presentation)

We show inkjet printed state-of-the-art perovskite solar cells with efficiencies of up to 12% which is an important step towards fully printed large scale production of photovoltaic perovskite devices. In comparison, the spin-coated reference achieves 13% efficiency. In both cases, the solar cell absorbers are prepared using a one-step process on a TiO2 compact layer without mesoporous intermediate layer as electron transport material and spiroMeOTAD as hole transport material. Moreover, we show that controlling printing parameters, like drop spacing and size, is essential to optimizing the final perovskite performance. Whereas parameters were initially controlled to be consistent with a final layer thicknesses known from literature, subsequent processes were aimed at also controlling crystallinity and roughness. To demonstrate the homogeneity of the printed devices, light beam induced current measurements (LBIC) were made. To evaluate the quality of the perovskite layer and the charge transfer efficiency in the device, time resolved photoluminescence measurements were conducted on the perovskite with and without electrical transport layers. Light soaking effects were also investigated and evaluated. Important differences between printed and spin-coated devices will be outlined, as well as other relevant parameters to optimize printed device performance.