Indium Selenide/Indium Tin Oxide Hybrid Films for Solution‐Processed Photoelectrochemical‐Type Photodetectors in Aqueous Media

Abstract

2D metal monochalcogenides have recently attracted interest for photoelectrochemical (PEC) applications in aqueous electrolytes. Their optical bandgap in the visible and near‐infrared spectral region is adequate for energy conversion and photodetection/sensing. Their large surface‐to‐volume ratio guarantees that the charge carriers are photogenerated at the material/electrolyte interface, where redox reactions occur, minimizing recombination processes. However, solution‐processed photoelectrodes based on these materials exhibit energy conversion efficiencies that are far from the current state of the art expressed by established technologies. This work reports a systematic morphological, spectroscopic, and PEC characterization of solution‐processed films of photoactive InSe flakes for PEC‐type photodetectors. By optimizing the thickness and hybridizing InSe flakes with electrically conductive Sn:In2O3 (ITO) nanocrystals, photoanodes with a significant photoanodic response in both acidic and alkaline media are designed, reaching responsivity up to 60.0 mA W−1 (external quantum efficiency = 16.4%) at +0.4 V versus RHE under visible illumination. In addition, a strategy based on the use of sacrificial agents (i.e., 2‐propanol and Na2SO3) is proposed to improve the stability of the InSe and ITO/InSe photodetectors. Our data confirm the potential of 2D InSe for PEC energy conversion and sensing applications, remarking the challenges related to InSe stability during anodic operation.

Engineering of the perovskite/electron-transporting layer interface with transition metal chalcogenides for improving the performance of inverted perovskite solar cells

“…87 Finally, bulk and exfoliated InSe exhibit various Raman peaks at similar positions, i.e., A 1 1g at ∼116 cm −1 , E 2 1g at ∼177 cm −1 , E 1 2g at ∼199 cm −1 , A 2u at ∼208 cm −1 , and A 2 1g at ∼227 cm −1 , which is consistent with previous studies. 63,64 The deposition of TMC nanosheets was carried out by spin coating their dispersion (formulated in chlorobenzene) onto the perovskite layer. Successive spin coating steps were applied to optimize the interlayer of TMC nanosheets at the perovskite/ PC 70 BM interface.…”

“…These materials exhibit exceptional optical, electrical, catalytic, and mechanical properties, making them suitable for numerous elds, including batteries, 1,2 supercapacitors, 3 , (photo)catalysis, [4][5][6][7][8] , (photo)transistors [9][10][11] and other optoelectronic devices. [12][13][14][15][16][17] One feature of TMCs is their band gap tunability, which makes them ideal for adjustable light absorption, e.g., serving as the photoactive layer in photovoltaic applications. However, photovoltaic devices using TMC-based photoactive layers currently exhibit insufficient power conversion efficiency (PCE) just above 5%.…”

“…71 This electron mobility is higher than those achieved by other high mobility 2D semiconducting materials, including MoS 2 . Based on its properties, 2D InSe has been used in photovoltaic devices, 72,73 as well as for (photo)electrochemical water splitting reactions, 64 photodetectors, 63,74 sensors, 75 thermoelectric devices, 76 and spintronic devices. 77 Overall, the above discussed TMCs represent interesting 2D materials for the engineering of the perovskite/ETL interface, aiming at improving the device PCE.…”

Structural and Optical Characterization of Electrochemically Deposited Indium Oxide Nanostructures for Photoelectrochemical Investigation

“…Different techniques for growing In 2 O 3 thin films have been reported, like pulsed laser deposition, , spray pyrolysis, chemical vapor deposition (CVD), ,, evaporation, cathodic electrodeposition, sputtering, thermal oxidation, and sol–gel , among which electrodeposition is a better choice. Electrodeposition is an attractive synthesis method because the growth parameters can easily be controlled to obtain thin films of diverse composition and properties; in addition, it is a low-temperature processing technique, the equipment and precursor materials are also inexpensive, and it has the capability to grow films on complex surfaces. − In most cases of electrodeposition of In 2 O 3 thin films, InCl 3 or In 2 (SO 4 ) 3 ·9H 2 O is used as the precursor, while stainless steel (ss), ITO/glass, and FTO/glass have been used as substrates. , The use of In 2 O 3 powder and titanium (Ti) foil as the source material and template in electrochemical deposition of In 2 O 3 thin films, however, has been scarcely explored.…”

“…Amid the different available TCOs like ZnO, CdO, and SnO 2 , the foremost is In transparency (70−95%) in the visible region, 7 and outstanding adhesion to the substrate. 11,12 Different techniques for growing In 2 O 3 thin films have been reported, like pulsed laser deposition, 5,6 spray pyrolysis, chemical vapor deposition (CVD), 9,13,14 evaporation, cathodic electrodeposition, 15 sputtering, thermal oxidation, and sol− gel 6,9 among which electrodeposition is a better choice. Electrodeposition is an attractive synthesis method because the growth parameters can easily be controlled to obtain thin films of diverse composition and properties; in addition, it is a low-temperature processing technique, the equipment and precursor materials are also inexpensive, and it has the capability to grow films on complex surfaces.…”