A large improvement in Cu2ZnSnSe4 solar cell efficiency is presented based on the introduction of a Ge superficial nanolayer. This improvement is explained by three complementary effects: the formation of a liquid Ge‐related phase, the possible reduction of Sn multicharge states, and the formation of GeOx nanoinclusions, which lead to an impressive solar cell (VOC) increase.

A functional DNAmicroarray was prepared through the laser-induced forward transfer (LIFT) technique. In a first experiment, droplets of a buffer solution were spotted onto a substrate at different laser pulse energies. This allowed one to determine that uniform spots with a diameter as small as 40μm could be obtained. In a second experiment, a microarray containing two different human cDNAs and a negative control was spotted through LIFT and submitted to a hybridization assay. The obtained results demonstrated the full functionality of the microarray, which allowed us to prove the viability of LIFT for the production of DNAmicroarrays.Postprint (published version

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Laser-induced forward transfer ͑LIFT͒ is a laser direct-write technique that offers the possibility of printing patterns with a high spatial resolution from a wide range of materials in a solid or liquid state, such as conductors, dielectrics, and biomolecules in solution. This versatility has made LIFT a very promising alternative to lithography-based processes for the rapid prototyping of biomolecule microarrays. Here, we study the transfer process through the LIFT of droplets of a solution suitable for microarray preparation. The laser pulse energy and beam size were systematically varied, and the effect on the transferred droplets was evaluated. Controlled transfers in which the deposited droplets displayed optimal features could be obtained by varying these parameters. In addition, the transferred droplet volume displayed a linear dependence on the laser pulse energy. This dependence allowed determining a threshold energy density value, independent of the laser focusing conditions, which acted as necessary conditions for the transfer to occur. The corresponding sufficient condition was given by a different total energy threshold for each laser beam dimension. The threshold energy density was found to be the dimensional parameter that determined the amount of the transferred liquid per laser pulse, and there was no substantial loss of material due to liquid vaporization during the transfer.

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In this work we study the optimization of laser-fired contact (LFC) processing parameters, namely laser power and number of pulses, based on the electrical resistance measurement of an aluminum single LFC point. LFC process has been made through four passivation layers that are typically used in c-Si and mc-Si solar cell fabrication: thermally grown silicon oxide (Si0 2 ), deposited phosphorus-doped amorphous silicon carbide (a-SiC/H(«)), aluminum oxide (A1 2 0 3 ) and silicon nitride (SiN^/H) films. Values for the LFC resistance normalized by the laser spot area in the range of 0.65-3 mil cm 2 have been obtained.

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