Semi-transparent perovskite solar cells with silver nanowires are stacked on CIGS and Si to achieve solid-state polycrystalline tandems with efficiency improvement.

Direct solar-to-fuels conversion can be achieved by coupling a photovoltaic device with water-splitting catalysts. We demonstrate that a solar-to-fuels efficiency (SFE) > 10% can be achieved with nonprecious, low-cost, and commercially ready materials. We present a systems design of a modular photovoltaic (PV)-electrochemical device comprising a crystalline silicon PV minimodule and lowcost hydrogen-evolution reaction and oxygen-evolution reaction catalysts, without power electronics. This approach allows for facile optimization en route to addressing lower-cost devices relying on crystalline silicon at high SFEs for direct solar-to-fuels conversion.istributed and grid-scale adoption of nondispatchable, intermittent, renewable-energy sources requires new technologies that simultaneously address energy conversion and storage challenges (1, 2). Coupling photovoltaics to drive catalytic fuelforming reaction, such as water splitting to generate H 2 , allows for direct solar-to-fuels conversion. The solar-generated H 2 can effectively be harnessed to electricity by fuel cell devices (3, 4) or converted to liquid fuels upon its combination with CO or CO 2 (5-7). For this technology to be effectively implemented, a solar-to-fuels conversion efficiency (SFE) of 10% or higher is desirable (8, 9).Direct photoelectrochemical (PEC) water splitting by a single absorber material has attracted a vast amount of attention (10, 11), and recent progress indicates improvements in the field (12, 13); but after decades of research, direct PEC faces three challenges to increase conversion efficiency: (i) Direct absorber band alignment is required to provide carriers with appropriate potential to both half reactions. Although such an alignment is difficult to achieve in a single material initially, any change in band alignment due to changing surface conditions can result in further efficiency degradation. This makes it challenging to design devices that maintain robust, high efficiencies in actual operation.(ii) The wide absorber bandgap (>1.23 eV; typically >1.6 eV) needed to drive the water-splitting reaction is not optimized for the solar spectrum, which results in a maximum SFE of only 7% (14-16). (iii) The absorbers are poor catalysts, and they are incapable of efficiently performing the four proton-coupled electron transfer chemistry (17-22) that is needed for water splitting.These deficiencies can be overcome by substituting a PEC device with a buried-junction photovoltaic (PV) device and an electrochemical catalyst (EC) system, forming a PV-EC tandem (23-27). In a buried-junction device, the electric field is generated at an internal junction within the semiconductor and is then coupled with water-splitting catalysts through ohmic contacts, which can either be conductive coatings directly deposited onto the PV or connected through wires to the electrodes. The buried junction relaxes the constraints imposed by a PEC device because it separates light absorption from catalysis, and does not require that the absorber be stable in ...

Light induced plating (LIP) of front grid contacts is an industry-scalable potential alternative to silver paste, but LIP requires an additional patterning step to create openings in the silicon nitride (SiN x ) antireflection coating (ARC) layer for metallization. One approach for patterning SiN x is masking and wet chemical etching. However, nitride etch rates can vary from cell to cell depending on the SiN x PECVD deposition parameters, previous processing steps, and etching solution usage and maintenance. Under-etching results in poor contact adhesion and over-etching results in undercutting and possible emitter damage. We demonstrate in situ real-time photoluminescence imaging (PLI) as a method to determine the point when SiN x has been fully removed. This method has the potential to be integrated into a commercial processing line to improve process control, uniformity, and repeatability.