Growth Of MoSe2 Research Articles

In Situ Studies on the Influence of Surface Symmetry on the Growth of MoSe2 Monolayer on Sapphire Using Reflectance Anisotropy Spectroscopy and Differential Reflectance Spectroscopy

The surface symmetry of the substrate plays an important role in the epitaxial high-quality growth of 2D materials; however, in-depth and in situ studies on these materials during growth are still limited due to the lack of effective in situ monitoring approaches. In this work, taking the growth of MoSe2 as an example, the distinct growth processes on Al2O3 (112¯0) and Al2O3 (0001) are revealed by parallel monitoring using in situ reflectance anisotropy spectroscopy (RAS) and differential reflectance spectroscopy (DRS), respectively, highlighting the dominant role of the surface symmetry. In our previous study, we found that the RAS signal of MoSe2 grown on Al2O3 (112¯0) initially increased and decreased ultimately to the magnitude of bare Al2O3 (112¯0) when the first layer of MoSe2 was fully merged, which is herein verified by the complementary DRS measurement that is directly related to the film coverage. Consequently, the changing rate of reflectance anisotropy (RA) intensity at 2.5 eV is well matched with the dynamic changes in differential reflectance (DR) intensity. Moreover, the surface-dominated uniform orientation of MoSe2 islands at various stages determined by RAS was further investigated by low-energy electron diffraction (LEED) and atomic force microscopy (AFM). By contrast, the RAS signal of MoSe2 grown on Al2O3 (0001) remains at zero during the whole growth, implying that the discontinuous MoSe2 islands have no preferential orientations. This work demonstrates that the combination of in situ RAS and DRS can provide valuable insights into the growth of unidirectional aligned islands and help optimize the fabrication process for single-crystal transition metal dichalcogenide (TMDC) monolayers.

Boosting Monolayer Transition Metal Dichalcogenides Growth by Hydrogen-Free Ramping during Chemical Vapor Deposition.

The controlled vapor-phase synthesis of two-dimensional (2D) transition metal dichalcogenides (TMDs) is essential for functional applications. While chemical vapor deposition (CVD) techniques have been successful for transition metal sulfides, extending these methods to selenides and tellurides often faces challenges due to uncertain roles of hydrogen (H2) in their synthesis. Using CVD growth of MoSe2 as an example, this study illustrates the role of a H2-free environment during temperature ramping in suppressing the reduction of MoO3, which promotes effective vaporization and selenization of the Mo precursor to form MoSe2 monolayers with excellent crystal quality. As-synthesized MoSe2 monolayer-based field-effect transistors show excellent carrier mobility of up to 20.9 cm2/(V·s) with an on-off ratio of 7 × 107. This approach can be extended to other TMDs, such as WSe2, MoTe2, and MoSe2/WSe2 in-plane heterostructures. Our work provides a rational and facile approach to reproducibly synthesize high-quality TMD monolayers, facilitating their translation from laboratory to manufacturing.

Unveiling the bifunctional roles of Cetyltrimethylammonium bromide in construction of Nb2CTx@MoSe2 heterojunction for fast potassium storage

Exploring robust electrode materials which could permit fast and reversible insertion/extraction of large K+ is a crucial challenge for potassium-ion batteries (PIBs). Smart interfacial design could facilitate electron/ion transport as well as assure the integrity of electrode. Herein, Cetyltrimethylammonium bromide (CTAB) was found to play bifunctional roles in construction of Nb2CTx@MoSe2 heterostructure. Firstly, functionalization of CTAB on the surface of Nb2CTx could influence the subsequent growth of MoSe2 by electrostatic effect, stereochemical effect and the synergetic Lewis acid-base interaction, leading to the formation of Nb2CTx@MoSe2 with tiled heterostructure. Secondly, the interlayer spacing of Nb2CTx was expanded from 0.77 to 1.21 nm owing to the pillar effect of CTAB. As excepted, the capacity retention was 80 % from 100 mA g−1 (406 mA h g−1) to 1000 mA g−1 concerning rate capability and the specific capacity maintained at 240 mA h g−1 (at 2000 mA g−1) over 300 cycles. The calculated DK values from Galvanostatic intermittent titration technique (GITT) measurement of the titled C-T-Nb2CTx@MoSe2@C electrode is two orders of magnitude larger than the traditional T-Nb2CTx@MoSe2@C electrode, further confirming intimate interface between MoSe2 and Nb2CTx could provide convenient potassium-ion transport channels and fast diffusion kinetics. Finally, ex-situ characterizations at different charging and discharging voltage stages, including ex-situ XRD/Raman/HRTEM/XPS have been carried out to reveal the potassium storage mechanism. This work provides a facile strategy for the regulation of interface engineering by the assist of CTAB which could extend to other MXenes-TMDs (Transition metal dichalcogenides) hybrid electrodes.

Out-of-plane preferential growth of 2D molybdenum diselenide nanosheets on laser-induced periodic surface structures

In this study, we explore the morphology and orientation of molybdenum diselenide, a Van der Waals 2D material, through isothermal closed space vapor deposition on both pristine and laser-structured substrates. Laser structuring is conducted on dielectric (sapphire), semiconductor (silicon), and conductive (titanium nitride) substrates using ultrashort laser pulses, resulting in smooth topographic changes such as laser-induced periodic surface structures (LIPSS) or selective ablation. Scanning electron microscopy (SEM) reveals the pivotal role of surface structuring in the growth of out-of-plane MoSe2 nanosheets. This effect is particularly pronounced on monocrystalline substrates like sapphire and silicon, exhibiting in-plane growth on pristine substrates. Additionally, Raman spectroscopy confirms the vertical orientation of flakes on structured substrates and highlights the presence of active edge sites by demonstrating an increased abundance of deposited material. Overall, our findings emphasize the controllability of directing the growth of MoSe2 flakes through appropriate pre-treatment of the substrate, with potential applications in various fields, including Surface-Enhanced Raman Scattering (SERS). Furthermore, the scalability, reproducibility, and applicability to any substrate make ultrashort laser structuration a promising general strategy for orienting 2D materials.

Low-temperature growth of MoSe2 and WSe2 nanostructures on flexible Mo and W metal foils

Low-temperature growth of MoSe2 and WSe2 nanostructures on flexible Mo and W metal foils

In-situ growth of MoSe2 on N-doped Ti3C2Tx for electrocatalytic hydrogen evolution in alkaline media

Abstract Serious environmental contamination and the energy crisis have heightened public desire for new renewable energy sources. Because of its high energy content and non-polluting qualities, hydrogen energy has emerged as a viable alternative to fossil fuels. Currently, high-purity hydrogen is typically produced through water electrolysis. The sensible use of electrocatalysts in this process can significantly minimize power usage in the electrolysis of water, which is of great significance to industrial production. However, the electrocatalyst that is inexpensive, has abundant reserves and performs well has yet to be discovered, severely restricting the promotion and application of hydrogen energy. In this paper, a MoSe2/N-doped Ti3C2TX heterostructure with notable electrocatalytic hydrogen evolution activity in an alkaline environment was fabricated via nitrogen doping and in-situ growth of molybdenum selenide. When the current density is 10 mA·cm-2, its overpotential and Tafel slope are 321.87 mV and 139.97 mV·dec-1, respectively. This work serves as a valuable experimental reference for the development of non-noble metal electrocatalysts based on two-dimensional materials.

Catalytic strategies for uniform monolayer MoSe2 growth in CVD processes

To facilitate the widespread utilization of devices based on two-dimensional transition metal dichalcogenide (TMDC) materials, addressing the challenge of producing large-area and uniform monolayers is crucial. In this study, we investigated the efficacy of various catalysts in promoting the growth of monolayer MoSe2 through chemical vapor deposition (CVD) as a potential solution to improve surface coverage and uniformity while maintaining the monolayer structure. Five distinct water-soluble catalysts (sodium chloride (NaCl), zinc chloride (ZnCl2), potassium hydroxide (KOH), potassium chloride (KCl), potassium oxalate (K2C2O4)) were employed in conjunction with a glass substrate for the CVD-based growth of monolayer MoSe2. We applied these catalyst solutions as thin layers onto SiO2/Si substrates to observe their specific catalytic effects on monolayer MoSe2 formation. MoSe2 was selected as the target material due to its promising characteristics within the TMDC family, particularly its high mobility. Our findings revealed that NaCl, ZnCl2, KCl, and K2C2O4 catalysts enhanced monolayer growth in the 2H phase on SiO2/Si substrates, while the glass substrate resulted in a hybrid 1T/2H MoSe2 structure, albeit with the highest surface coverage. Furthermore, the use of a catalyst allowed us to bypass the laborious transfer step by enabling direct growth of the MoSe2 flakes on the Si/SiO2 substrate, eliminating the risk of flake damage arising from the transfer process. Among the catalyst solutions, NaCl yielded the most homogeneous MoSe2 monolayer growth with relatively high coverage.

Large area MoSe2 and MoSe2/Bi2Se3 films on sapphire (0001) for near-infrared photodetection

The fabrication of heterojunction-based photodetectors (PDs) is well known for the enhancement of PDs performances, tunable nature of photoconductivity, and broadband application. Herein, the PDs based on MoSe2 and MoSe2/Bi2Se3 heterojunction on sapphire (0001) substrates were deposited using a r.f. magnetron sputtering system. The high-resolution x-ray diffraction and Raman spectroscopy characterizations disclosed the growth of the 2-H phase of MoSe2 and the rhombohedral phase of Bi2Se3 thin films on sapphire (0001). The chemical and electronic states of deposited films were studied using x-ray photoelectron spectroscopy and revealed the stoichiometry growth of MoSe2. We have fabricated metal-semiconductor–metal type PD devices on MoSe2 and MoSe2/Bi2Se3 heterojunction and the photo-response measurements were performed at external voltages of 0.1–5 V under near-infrared (1064 nm) light illumination. The bare MoSe2 PD device shows positive photoconductivity behavior whereas MoSe2/Bi2Se3 heterojunction PD exhibits negative photoconductivity. It was found that the responsivity of MoSe2 and MoSe2/Bi2Se3 heterojunction PDs is ~ 1.39 A W−1 and ~ 5.7 A W−1, respectively. The enhancement of photoresponse of MoSe2/Bi2Se3 PD nearly four-fold compared to bare MoSe2 PD shows the importance of heterojunction structures for futuristics optoelectronic applications.

NaCl-assisted chemical vapor deposition growth of MoSe2 and MoSe2/h-BN heterostructure

As a typical two-dimensional (2D) transition metal dichalcogenides (TMDCs), MoSe2 has attracted lots of interest due to its electronic and optical properties in recent years. The controllable synthesis of 2D MoSe2 and its heterostructure is of considerable importance for achieving diverse applications. Herein, we realized the controlled growth of MoSe2 by atmospheric pressure chemical vapor deposition (APCVD) method through using NaCl as the promoter. Raman and photoluminescence (PL) spectroscopy have been used to investigate the optical properties of MoSe2 domains with different layers. The dependence of structures on synthetic parameter is systematically investigated by tuning the growth conditions. On this basis, the monolayer MoSe2 was constructed on CVD-grown hexagonal boron nitride (h-BN) by an all-CVD approach. Detailed characterizations indicate that MoSe2 deposited on h-BN exhibits improved optical properties as compared to those on SiO2/Si. Our results could enrich the understanding for growth of TMDCs, advocating further investigation of their intrinsic properties and a variety of device applications.

Enhancing PEO coating on TC6 alloy through in-situ synthesis of MoSe2—Towards more efficient wear-reducing lubrication and wear resistance

Plasma electrolytic oxidation (PEO) has demonstrated significant enhancements in the mechanical properties and corrosion resistance of titanium alloys. Despite these advantages, the presence of micropores and microcracks in the coating can still detrimentally impact tribological properties. This paper introduces a novel approach involving the in-situ growth of a surface structure. The resulting interface structure exhibits outstanding tribological properties under a load of 3 N and a speed of 1.5 cm/s. In contrast to prior studies, improvements are made to the electrical parameters and electrolyte formula of Plasma electrolytic oxidation, facilitating the in-situ growth of MoSe2. This results in the formation of a lubricating layer and a robust TiO2 ceramic coating with excellent adhesion. A systematic analysis of friction, wear characteristics, reveals that MoSe2 in situ grow on the surface of the PEO coating, within micropores, microcracks, and crater structures after hydrothermal treatment. This process significantly enhances the microporous structure of the coating, with the MoSe2 film forming a dense and uniform interlocking layer with the PEO lower layer. Dry friction test experiments demonstrate a 33.7% reduction in friction coefficient and a 29% decrease in wear rate compared to the PEO sample, indicating the synergistic effect between the MoSe2 film and the PEO coating.

Toward an understanding of the mechanism of mixed-salt-mediated CVD growth of MoSe2

The use of liquid precursors in chemical vapor deposition (CVD) techniques is advantageous for growing large-area, uniform two-dimensional (2D) transition-metal dichalcogenides (TMDs) compared to conventional methods using solid precursors. While various liquid precursors have been explored, recent studies highlight the use of mixed-salt precursors for growing uniform and wafer-scale TMDs. In this study, we propose a growth mechanism and present our findings on the epitaxial growth of MoSe2 domains as a function of annealing/growth time and H2 flow rate using Na2MoO4 and Na2SeO3 mixed-salt precursors. We confirm that the increase in the annealing time enhances the distribution of spin-coated precursors, leading to a rise in flake number density. On the other hand, prolonged growth time results in better-aligned MoSe2 flakes along the c-sapphire substrate step-edges. A significant finding is the dynamic diffusion of dendritic structures within large domains over the growth period, owing to the constant dissolution and recrystallization in the presence of residual liquid alloys. An increase in the H2 flow during CVD growth yields small, triangular domains aligned with the step edges, a result of the efficient reduction of precursor alloys and subsequent selenization. Our results provide an insight on achieving uniform and aligned morphology in CVD growth of 2D TMDs using liquid-phase precursors, a crucial step toward large-area fabrication.

Modulating the electronic structure at the interface of CoSe and MoSe2 for enhanced electrocatalytic hydrogen evolution reaction

Metal selenide is a group of promising electrocatalysts for hydrogen evolution reaction (HER). However, Molybdenum selenide (MoSe2) exhibits sluggish HER kinetics in alkaline electrolytes mainly due to inherently inferior electrical conductivity and disappearance of edge active sites. Herein, we reported the preparation of MOF-derived CoSe/MoSe2 heterogeneous structure with excellent electrocatalytic activity in HER. The overpotential of CoSe/MoSe2 at current density of 10 mA cm−2 was only 135 mV. DFT calculations and characterization results revealed that the excellent HER electrocatalytic performance was attributed to the fabrication of the CoSe/MoSe2 interface. As-fabricated interface not only improved the electrical conductivity through modulating the electronic structure, but also enhanced H∗ adsorption thereby alleviating the energy barrier. Moreover, CoSe derived from the ZIF-67 with porous structure can provide the larger surface for the uniform growth of MoSe2 and then expose abundant edge active sites of MoSe2. This work enriched and developed the strategies for the designing of more highly efficient electrocatalysts via the heterogeneous interface modulation.

Hybrid Alkali Salt Catalysts‐Promoted CVD Growth of 2D MoSe2–WSe2 and WSe2–MoSe2 Lateral Heterostructures

AbstractA scalable growth of atomically‐thin 2D transition metal dichalcogenides (TMDs) with defect‐free large‐area surfaces is crucial for developing high‐performing optoelectronic devices. Herein, a method to grow large‐area, high‐quality MoSe2 monolayers, MoSe2–WSe2, and WSe2–MoSe2 lateral heterostructures using molten salt‐based chemical vapor deposition (CVD) is systematically reported. First, effects of isolated inorganic (sodium chloride (NaCl) and sodium nitrate (NaNO3)), organic (Perylene–3,4,9,10–tetracarboxylic acid tetrapotassium salt (PTAS), mixed inorganic (NaCl/NaNO3), and hybrid organic–inorganic (PTAS/NaCl/NaNO3) salt catalysts on the CVD growth and optoelectronic quality of MoSe2 monolayers and their lateral heterostructures with WSe2 in MoSe2–WSe2 and WSe2–MoSe2 assemblies are investigated. Results show that molten salt catalysts (NaCl/NaNO3 and PTAS/NaCl/NaNO3) support high‐quality, large‐area growth of MoSe2 monolayers with low defect density. The mixed inorganic salt supports growth of MoSe2–WSe2 lateral heterostructures but not their counterpart. Meanwhile, WSe2–MoSe2 lateral heterostructures are optimally grown, supported by the hybrid organic–inorganic salt. These results are ascribed to the difference in the associated kinetic and thermodynamic mechanisms for the growths of MoSe2 and WSe2 as starting materials. Last, it is confirmed that optoelectronic quality of realized heterostructures and monolayers is improved compared to their mechanically exfoliated counterparts. The obtained high‐quality, large‐area 2D TMD heterostructures can be useful for various optoelectronic applications.

Formation mechanism of mirror twin grain boundaries in molecular beam epitaxy grown monolayer WSe2–MoSe2 lateral heterojunctions

Mirror twin grain boundary (MTB) defects, being a special type of high-symmetry one-dimensional (1D) defects in two-dimensional atomically thin transition metal dichalcogenides (TMDCs), have received considerable interest due to their unique structures and intriguing 1D properties. However, formation and distribution of MTBs in hybrid TMDC materials such as heterojunction remain scarcely studied. Herein, we investigate the spatial distribution, lattice registry and formation mechanism of MTBs in molecular beam epitaxy grown monolayer WSe2–MoSe2 lateral heterojunctions using atomic-resolution annular dark-field scanning transmission electron microscopy (ADF-STEM). MTBs manifest a much higher density in MoSe2 than in WSe2 domains with a few of them spanning coherently across the domain interface. Compositionally, a Mo-dominant rather than W-dominant configuration was observed in those MTBs located in WSe2 domains and its origin can be attributed to the preferable Mo substitution to W along the MTBs occurring at the later MoSe2 growth period. This proposed mechanism is supported by ab-initio density functional theory calculations and substitution dynamics captured by in-situ ADF-STEM. The present study deepens our understanding of MTBs in heterostructured TMDCs, which may also serve as an excellent platform for the exploration of intriguing 1D physics.

Crystal violet as CMOS-compatible alkali-free promoter for CVD growth of MoSe2 monolayers: Comparative surface analysis with alkali-based promoter

The wafer-level growth of transition metal dichalcogenides (TMDs) using chemical vapor deposition (CVD) is essential for industrial applications involving complementary metal-oxide-semiconductor (CMOS) processes. In the CVD processes of TMDs, promoters containing alkali elements such as Na and K are typically used to obtain high-quality crystals. However, the use of alkali elements is rigorously restricted in CMOS processes because of contamination problems. In this study, we investigated crystal violet (CV) as a promising alkali-free promoter in the CVD growth of MoSe2. Particularly, the surface properties were intensively examined by optical, chemical, and topographical analyses and compared to those of samples prepared with NaOH as a representative alkali-based promoter. Na residues causing a doping effect were observed in the NaOH process, whereas the doping effect was negligible in the CV process. After the transfer process from the as-grown state, the strain effect in the NaOH process was prominently changed, resulting in wrinkles on MoSe2, whereas the wrinkles were negligible in the CV process, suggesting relatively smaller strain accumulation in the CV process during crystal growth. Our results showed the feasibility of CV as an alkali-free promoter for utilizing CVD-grown TMDs in industrial CMOS processes.

Free standing MoSe2 growth on porous Graphite-Like membranes for water splitting

Clean hydrogen made from water-splitting through the hydrogen evolution reaction (HER) is important for sustainability and reducing pollution. Exploration of high-efficiency Pt-free electrochemical catalysts for HER is considered a great challenge for the development of sustainable and carbon dioxide-free energy conversion systems.For that, electrocatalytic electrodes made of self-standing binder-free materials have been extensively employed in hydrogen production. Herein, the gelatin and graphene oxide cryogels were cryogeleted and then carbonized to create a unique interconnecting macroporous conducting carbon membrane. The conducting membrane is employed as a substrate for growing MoSe2nanosheets vertically using a simple solvothermal process. The electrochemical performance of the self-standing MoSe2-based heterogeneous binder-free materials was successively evaluated for HER.The excellent electrochemical hydrogen generation exhibited a low onset potential of −0.15 Vvsthe reversible hydrogen electrode and a Tafel slope of 51 mV/decade. In addition, remarkable stability with no current decay for over 20,000 s of testing was observed. The perpendicularly oriented nanostructure of the electrocatalyst on a highly carbon-porous electrode favored more exposedactive sites. Such, an open 3D structure leads to an easily diffused electrolyte in which the exposed active edges of MoSe2nanostructures are a key issue to fully realizing the excellent electrochemical properties.

One and two-dimensional control growth of MoSe2−x nanostructures

Here, we successfully synthesize the 1D nanorods and 2D nanosheets of defective MoSe2 by a hydrothermal method. It is observed that the morphology of MoSe2−x samples is well controlled by the amount of reducing agent added during the synthesis. The SEM and TEM images reveal that the mixed dimensional 1D/2D nanorods/nanosheets are present in a sample prepared with 40 mmol of NaBH4. The individual 1D nanorod and 2D nanosheet morphology was observed for samples prepared with 60 and 80 mmol respectively. The defective 1D nanorods and 2D nanosheets exhibit different crystallographic planes dispute to posing 2 H-hexagonal crystal structure. The samples containing 2D nanosheets exhibit better electrocatalytic activity than 1D nanorods due to the presence of catalytic active edge sites.

Synergistic effect stemming from vertically anchored seamless 2D MoSe2 nanosheets on 1D NiTiO3 nanofibers toward CO2 photoreduction

Herein, nickel titanate nanofiber/molybdenum diselenide nanosheet (NiTiO3 NF/MoSe2) heterostructures were prepared and their photocatalytic CO2 photoreduction performance was assessed. The heterostructures were synthesized via a facile two-step synthesis route combining an electrospinning technique followed by a solvothermal method. The MoSe2 nanosheets were vertically anchored to the surface of NiTiO3 NF, thereby increasing the number of exposed active edges that are pivotal to photocatalytic performance. By tuning the loading of MoSe2 in the heterostructure, the optimal condition was obtained for the fabrication of the NiTiO3 NF/MoSe2 heterojunctions. The as-prepared heterojunctions exhibited higher photocatalytic activity than pure NiTiO3 NF and MoSe2 for the photocatalytic reduction of CO2 under ultraviolet-visible light irradiation. Among the several hybrid samples, the optimal sample displayed a 6.6- and 7.7-fold enhanced production of CO (386 µmol g–1) compared with that of pure NiTiO3 NF (58 µmol g–1) and pure MoSe2 (50 µmol g–1), respectively, with overall CO2 selectivity of 86%. This enhanced photocatalytic activity was attributed to synergy created by tailored loading of MoSe2 nanosheets onto the 1D NiTiO3 NF. This hierarchical growth of MoSe2 over NiTiO3 NF provided more exposed edge sites, enhanced light absorption over the entire spectrum, and improved separation of photogenerated electrons and holes at the NiTiO3 NF/MoSe2 heterojunction interface. Such NiTiO3 NF/MoSe2 heterojunctions with broad spectral photocatalytic performance have potential applications in water splitting and water treatment.

Study on the selenization behavior of a DC magnetron reactive sputtered molybdenum nitride layers

Numerous strategies have been investigated in the field of thin film photovoltaic technology to minimize the thickness of the MoSe2 layer formation during high-temperature selenization. Herein, a phase of molybdenum nitride (γ-Mo2N) is developed to prevent the production of excessive MoSe2. The Mo layers were sputtered at various N2 partial pressures (PN2, 0–0.67 mT) and then selenized for 10 min at 460 °C in a rapid thermal process (RTP) unit. The selenized film prepared at PN2 of 0.26 mT exhibited controlled MoSe2 thickness of ∼100 nm along with preferable (100) and (110) orientations. At higher PN2 of 0.51 and 0.67 mT, the thickness of MoSe2 was increased and had (002) plane as preferred orientation, which are unfavorable conditions. As a result, a PN2 of 0.26 mT has the most potent inhibitory effect on MoSe2 growth and the generation of favorable (100) and (110) orientations.

Influence of the Rear Interface on Composition and Photoluminescence Yield of CZTSSe Absorbers: A Case for an Al2O3 Intermediate Layer.

The rear interface of kesterite absorbers with Mo back contact represents one of the possible sources of nonradiative voltage losses (ΔVoc,nrad) because of the reported decomposition reactions, an uncontrolled growth of MoSe2, or a nonoptimal electrical contact with high recombination. Several intermediate layers (IL), such as MoO3, TiN, and ZnO, have been tested to mitigate these issues, and efficiency improvements have been reported. However, the introduction of IL also triggers other effects such as changes in alkali diffusion, altered morphology, and modifications in the absorber composition, all factors that can also influence ΔVoc,nrad. In this study, the different effects are decoupled by designing a special sample that directly compares four rear structures (SLG, SLG/Mo, SLG/Al2O3, and SLG/Mo/Al2O3) with a Na-doped kesterite absorber optimized for a device efficiency >10%. The IL of choice is Al2O3 because of its reported beneficial effect to reduce the surface recombination velocity at the rear interface of solar cell absorbers. Identical annealing conditions and alkali distribution in the kesterite absorber are preserved, as measured by time-of-flight secondary ion mass spectrometry and energy-dispersive X-ray spectroscopy. The lowest ΔVoc,nrad of 290 mV is measured for kesterite grown on Mo, whereas the kesterite absorber on Al2O3 exhibits higher nonradiative losses up to 350 mV. The anticipated field-effect passivation from Al2O3 at the rear interface could not be observed for the kesterite absorbers prepared by the two-step process, further confirmed by an additional experiment with air annealing. Our results suggest that Mo with an in situ formed MoSe2 remains a suitable back contact for high-efficiency kesterite devices.