Transition Metal Dichalcogenide Films Research Articles

Two-Step Conversion of Metal and Metal Oxide Precursor Films to 2D Transition Metal Dichalcogenides and Heterostructures.

The widely studied class of two-dimensional (2D) materialsknown as transition metal dichalcogenides (TMDs) are now well-poised to be employed in real-world applications ranging from electronic logic and memory devices to gas and biological sensors. Several scalable thin film synthesis techniques have demonstrated nanoscale control of TMD material thickness, morphology, structure, and chemistry and correlated these properties with high-performing, application-specific device metrics. In this review, the particularly versatile two-step conversion (2SC) method of TMD film synthesis is highlighted. The 2SC technique relies on deposition of a solid metal or metal oxide precursor material, followed by a reaction with a chalcogen vapor at an elevated temperature, converting the precursor film to a crystalline TMD. Herein, the variables at each step of the 2SC process including the impact of the precursor film material and deposition technique, the influence of gas composition and temperature during conversion, as well as other factors controlling high-quality 2D TMD synthesis are considered. The specific advantages of the 2SC approach including deposition on diverse substrates, low-temperature processing, orientation control, and heterostructure synthesis, among others, are featured. Finally, emergent opportunities that take advantage of the 2SC approach are discussed to include next-generation electronics, sensing, and optoelectronic devices, as well as catalysis for energy-related applications.

Low-Temperature Synthesis of WSe2 by the Selenization Process under Ultrahigh Vacuum for BEOL Compatible Reconfigurable Neurons.

Low-temperature large-area growth of two-dimensional (2D) transition-metal dichalcogenides (TMDs) is critical for their integration with silicon chips. Especially, if the growth temperatures can be lowered below the back-end-of-line (BEOL) processing temperatures, the Si transistors can interface with 2D devices (in the back end) to enable high-density heterogeneous circuits. Such configurations are particularly useful for neuromorphic computing applications where a dense network of neurons interacts to compute the output. In this work, we present low-temperature synthesis (400 °C) of 2D tungsten diselenide (WSe2) via the selenization of the W film under ultrahigh vacuum (UHV) conditions. This simple yet effective process yields large-area, homogeneous films of 2D TMDs, as confirmed by several characterization techniques, including reflection high-energy electron diffraction, atomic force microscopy, transmission electron microscopy, and different spectroscopy methods. Memristors fabricated using the grown WSe2 film are leveraged to realize a novel compact neuron circuit that can be reconfigured to enable homeostasis.

Dual-Limit Growth of Large-Area Monolayer Transition Metal Dichalcogenides.

The large-scale growth of monolayer transition metal dichalcogenide (TMDC) films is a determinant for the implementation of two-dimensional materials in industrial applications. However, the simultaneous realization of uniform monolayer thickness and large-area coverage is still a challenge, because it requires precise control of reaction kinetics in both space and time dimensions. Herein, we achieve a variety of large-area monolayer TMDCs films by a dual-limit growth (DLG) that is realized through nanoporous carbon nanotube (CNT) films. In the DLG, a precursor-loaded CNT film placed face-to-face with a substrate provides a space-limited environment facilitating the monolayer growth, while the byproducts formed in the CNT film timely limits the supply of precursors released from nanopores of the CNT film, inhibiting the growth of multilayer TMDCs on the substrate. Consequently, large-area monolayer TMDC films are grown in a wide range of reaction times and show good homogeneity in thickness, optical properties, and device performance over the entire substrate. The DLG strategy is widely applicable for the growth of a variety of TMDC films including WSe2, MoS2, MoSe2, WS2, and ReS2. Our work provides a universal strategy to attain large-area monolayer TMDC films that can be used in practical applications of integrated circuits.

Independent enhancement of the in-plane Seebeck effect in 2D PtSe2/PtSe2 homostructures via a facile interface tuning method

Atomically thin two-dimensional (2D) transition-metal dichalcogenide (TMDC) films have emerged as promising semiconducting materials for use in thermoelectric (TE) applications. However, the utilization of such materials remains challenging owing to the relatively high intrinsic resistance as the size of the TMDC thin films increases to the centimeter scale. These 2D TMDC films can also form vertically stacked homo- or heterostructures at large interfaces with other 2D TMDC films, resulting in unique TE properties at room temperature. This article reports on the in-plane TE properties when the interfaces formed within a PtSe2/PtSe2 (3 nm/3 nm) homostructure are modulated as a function of O2 plasma treatment time. The results show enhanced Seebeck coefficients compared with that of the single-layer PtSe2 with the same thickness. The independent enhancement in the Seebeck coefficient while keeping the electrical conductivity leads to a substantial increase in the power factor. Such extra Seebeck voltage in 2D PtSe2/PtSe2 homostructures is mainly as a result of momentum exchange by charge carriers caused by the temperature gradient in the vertical direction, which occurs in-plane Seebeck coefficient measurements, at the interface between the PtSe2 layers in the in-plane temperature gradient along the samples. These results resemble the characteristics of the phonon drag effect at low temperatures, which can independently increase the Seebeck coefficient at room temperature.

Large-area single-crystal TMD growth modulated by sapphire substrates.

Transition metal dichalcogenides (TMDs) have recently attracted extensive attention due to their unique physical and chemical properties; however, the preparation of large-area TMD single crystals is still a great challenge. Chemical vapor deposition (CVD) is an effective method to synthesize large-area and high-quality TMD films, in which sapphires as suitable substrates play a crucial role in anchoring the source material, promoting nucleation and modulating epitaxial growth. In this review, we provide an insightful overview of different epitaxial mechanisms and growth behaviors associated with the atomic structure of sapphire surfaces and the growth parameters. First, we summarize three epitaxial growth mechanisms of TMDs on sapphire substrates, namely, van der Waals epitaxy, step-guided epitaxy, and dual-coupling-guided epitaxy. Second, we introduce the effects of polishing, cutting, and annealing processing of the sapphire surface on the TMD growth. Finally, we discuss the influence of other growth parameters, such as temperature, pressure, carrier gas, and substrate position, on the growth kinetics of TMDs. This review might provide deep insights into the controllable growth of large-area single-crystal TMDs on sapphires, which will propel their practical applications in high-performance nanoelectronics and optoelectronics.

Electrodeposition of Transition Metal Dichalcogenide Thin- Films from Non-Aqueous Solvents

Transition metal dichalcogenides (TMDCs) are an interesting group of 2D materials characterised with a layered structure analogous to graphene and they possess unique electronic and optical properties, especially when in the few- and mono-layer form. Developing scalable techniques for depositing TMDCs is a major challenge which needs to be overcome to fabricate functional devices with these materials. Electrodeposition is an industrially relevant technique that has some key advantages over other conventional deposition methods. It is a low cost and easily scalable technique and could be used for obtaining complex nanoscale features and for depositing over topologically demanding surfaces. Even though the electrodeposition of MoS2 has been achieved both in aqueous and non-aqueous electrolytes, not much progress has been made in the deposition of other TMDC materials. Tungsten based TMDCs such as WS2 and WSe2 are shown to be very promising materials in different applications, however electrodepositing them remains extremely challenging. One of the major obstacles here is developing electrochemically active precursors which are compatible with the electrolyte system and able to deliver both the tungsten and chalcogens to the electrolyte. Controlling and optimizing the deposition process to obtain few- and mono-layer TMDCs is another challenge. In addition, the choice of substrates for deposition is very important, especially for direct growth of ultra-thin TMDCs. Electrodeposition, being a bottom-up deposition method, would benefit from an atomically thin and smooth substrate such as graphene for depositing few- and mono-layer TMDCs.Here we present non-aqueous electroplating as a scalable alternative technique for tungsten-based TMDC deposition, with WS2 and WSe2 as examples. Tailored single source precursors were developed to use in non-aqueous electrolytes. WS2 was electrodeposited from dichloromethane (CH2Cl2) using the [NEt4]2[WS2Cl4] precursor. WSe2 was then electrodeposited from acetonitrile (CH3CN) electrolyte using [WSeCl4] as the precursor. Electrochemical quartz crystal microbalance (EQCM) studies were performed to optimize the deposition process and to probe the mechanism of precursor electrochemistry. Electrochemical deposition parameters were then carefully adjusted to obtain few- and mono-layer TMDCs. Patterned graphene electrodes were used as an atomically thin and smooth platform for the deposition of few- and mono-layer WS2. Few-layer TMDC films obtained on graphene were found to be much smoother than films deposited on other standard substrates such as titanium nitride (TiN) or Pt. These TMDC/graphene structures gave interesting 2D heterostructures which are technologically important for different applications.This work was funded by EPSRC grant references EP/V062689/1, EP/V062387/1 and EP/P025137/1

Efficiency limit of transition metal dichalcogenide solar cells

Ultrathin transition metal dichalcogenide (TMD) films show great promise as absorber materials in high-specific-power (i.e., high-power-per-weight) solar cells, due to their high optical absorption, desirable band gaps, and self-passivated surfaces. However, the ultimate performance limits of TMD solar cells remain unknown today. Here, we establish the efficiency limits of multilayer (≥5 nm-thick) MoS2, MoSe2, WS2, and WSe2 solar cells under AM 1.5 G illumination as a function of TMD film thickness and material quality. We use an extended version of the detailed balance method which includes Auger and defect-assisted Shockley-Read-Hall recombination mechanisms in addition to radiative losses, calculated from measured optical absorption spectra. We demonstrate that single-junction solar cells with TMD films as thin as 50 nm could in practice achieve up to 25% power conversion efficiency with the currently available material quality, making them an excellent choice for high-specific-power photovoltaics.

Characterization of 2D Transition Metal Dichalcogenides Through Anisotropic Exciton Behaviors.

This study reports the first attempt to characterize the quality, defects, and strain of as-grown monolayer transition metal dichalcogenide (TMDC)-based 2D materials through exciton anisotropy. A standard ellipsometric parameter (Ψ) to observe anisotropic exciton behavior in monolayer 2D materials is used. According to the strong exciton effect from phonon-electron coupling processes, the change in the exciton in the Van Hove singularity is sensitive to lattice distortions such as defects and strain. In comparison with Raman spectroscopy, the variations in exciton anisotropy in Ψ are more sensitive for detecting slight changes in the quality and strain of monolayer TMDC films. Moreover, the optical power requirement for TMDC characterization through exciton anisotropy in Ψ is ≈10-5mWcm-2, which is significantly less than that of Raman spectroscopy (≈106mWcm-2). The standard deviation of the signals varies with strain (defects) in Raman spectra and exciton anisotropies in Ψ are 0.700 (0.795) and 0.033 (0.073), indicating that exciton anisotropy is more sensitive to slight changes in the quality of monolayer TMDC films.

Selective Control of Phases and Electronic Structures of Monolayer TaTe2.

Transition metal dichalcogenide (TMDC) films exhibit rich phases and superstructures, which can be controlled by the growth conditions as well as post-growth annealing treatment. Here, the selective growth of monolayer TaTe2 films with different phases as well as superstructures using molecular beam epitaxy (MBE) is reported. Monolayer 1H-TaTe2 and 1T-TaTe2 films can be selectively controlled by varying the growth temperature, and their different electronic structures are revealed through the combination of angle-resolved photoemission spectroscopy measurements (ARPES) and first-principles calculations. Moreover, post-growth annealing of the 1H-TaTe2 film further leads to a transition from a superstructure to a new 2 × 2 superstructure, where two gaps are observed in the electronic structure and persist up to room temperature. First-principles calculations reveal the role of the phonon instability in the formation of superstructures and the effect of local atomic distortions on the modified electronic structures. This work demonstrates the manipulation of the rich phases and superstructures of monolayer TaTe2 films by controlling the growth kinetics and post-growthannealing.

The Role of Carbon in Metal-Organic Chemical Vapor Deposition-Grown MoS2 Films.

Acquiring homogeneous and reproducible wafer-scale transition metal dichalcogenide (TMDC) films is crucial for modern electronics. Metal-organic chemical vapor deposition (MOCVD) offers a promising approach for scalable production and large-area integration. However, during MOCVD synthesis, extraneous carbon incorporation due to organosulfur precursor pyrolysis is a persistent concern, and the role of unintentional carbon incorporation remains elusive. Here, we report the large-scale synthesis of molybdenum disulfide (MoS2) thin films, accompanied by the formation of amorphous carbon layers. Using Raman, photoluminescence (PL) spectroscopy, and transmission electron microscopy (TEM), we confirm how polycrystalline MoS2 combines with extraneous amorphous carbon layers. Furthermore, by fabricating field-effect transistors (FETs) using the carbon-incorporated MoS2 films, we find that traditional n-type MoS2 can transform into p-type semiconductors owing to the incorporation of carbon, a rare occurrence among TMDC materials. This unexpected behavior expands our understanding of TMDC properties and opens up new avenues for exploring novel device applications.

Probing Carrier Dynamics in Large-Scale MBE-Grown PtSe2 Films by Terahertz Spectroscopy.

Atomically thin platinum diselenide (PtSe2) films are promising for applications in the fields of electronics, spintronics, and photodetectors owing to their tunable electronic structure and high carrier mobility. Using terahertz (THz) spectroscopy techniques, we investigated the layer-dependent semiconducting-to-metallic phase transition and associated intrinsic carrier dynamics in large-scale PtSe2 films grown by molecular beam epitaxy. The uniformity of large-scale PtSe2 films was characterized by spatially and frequency-resolved THz-based sheet conductivity mapping. Furthermore, we use an optical-pump-THz-probe technique to study the transport dynamics of photoexcited carriers and explore light-induced intergrain carrier transport in PtSe2 films. We demonstrate large-scale THz-based mapping of the electrical properties of transition metal dichalcogenide films and show that the two noncontact THz-based approaches provide insight in the spatial and temporal properties of PtSe2 films.

Temperature-Dependent Structural and Electrical Properties of Metal-Organic CVD MoS2 Films.

Metal-Organic CVD method (MOCVD) allows for deposition of ultrathin 2D transition metal dichalcogenides (TMD) films of electronic quality onto wafer-scale substrates. In this work, the effect of temperature on structure, chemical states, and electronic qualities of the MOCVD MoS2 films were investigated. The results demonstrate that the temperature increase in the range of 650 °C to 950 °C results in non-monotonic average crystallite size variation. Atomic force microscopy (AFM), transmission electron microscopy (TEM), and Raman spectroscopy investigation has established the film crystal structure improvement with temperature increase in this range. At the same time, X-Ray photoelectron spectroscopy (XPS) method allowed to reveal non-stoichiometric phase fraction increase, corresponding to increased sulfur vacancies (VS) concentration from approximately 0.9 at.% to 3.6 at.%. Established dependency between the crystallite domains size and VS concentration suggests that these vacancies are form predominantly at the grain boundaries. The results suggest that an increased Vs concentration and enhanced charge carriers scattering at the grains' boundaries should be the primary reasons of films' resistivity increase from 4 kΩ·cm to 39 kΩ·cm.

Electroluminescence from Megasonically Solution-Processed MoS2 Nanosheet Films.

Due to their superior optoelectronic properties, monolayer two-dimensional (2D) transition metal dichalcogenides (TMDs) have attracted significant attention for electroluminescent devices. However, challenges in isolating optoelectronically active TMD monolayers using scalable liquid phase exfoliation have precluded electroluminescence in large-area, solution-processed TMD films. Here, we overcome these limitations and demonstrate electroluminescence from molybdenum disulfide (MoS2) nanosheet films by employing a monolayer-rich MoS2 ink produced by electrochemical intercalation and megasonic exfoliation. Characteristic monolayer MoS2 photoluminescence and electroluminescence spectral peaks at 1.88-1.90 eV are observed in megasonicated MoS2 films, with the emission intensity increasing with film thickness over the range 10-70 nm. Furthermore, employing a vertical light-emitting capacitor architecture enables uniform electroluminescence in large-area devices. These results indicate that megasonically exfoliated MoS2 monolayers retain their direct bandgap character in electrically percolating thin films even following multistep solution processing. Overall, this work establishes megasonicated MoS2 inks as an additive manufacturing platform for flexible, patterned, and miniaturized light sources that can likely be expanded to other TMD semiconductors.

Synthesis of Few-Layered Transition-Metal Dichalcogenides by Ion Implantation of Chalcogen and Metal Species into Sapphire.

The growth of transition-metal dichalcogenides (TMDCs) has been performed so far using most established thin-film growth techniques (e.g., vapor phase transport, chemical vapor deposition, molecular beam epitaxy, etc.). However, because there exists no self-limiting mechanism for the growth of TMDCs, none of these techniques allows precise control of the number of TMDC layers over large substrate areas. Here, we explore the ion implantation of the parent TMDC atoms into a chemically neutral substrate for the synthesis of TMDC films. The idea is that once all of the ion-implanted species have reacted together, the synthesis reaction stops, thereby effectively stopping growth. In other words, even if there is no self-limiting mechanism, growth stops when the nutrients are exhausted. We have co-implanted Mo and S ions into c-oriented sapphire substrates using various doses corresponding to 1- to 5-layer atom counts. We find that the subsurface region of the sapphire substrates is amorphized by the ion implantation process, at least for implanted doses of 2-layer atom counts and over. For all doses, we have observed the formation of MoS2 material inside the sapphire after postimplantation annealing between 800 and 850 °C. We report that the order of implantation (i.e., whether S or Mo is implanted first) is an important parameter. More precisely, samples for which S is implanted first tend to yield thin crystals with a large lateral extension (more than 200 nm for 5-layer doses) and mainly located at the interface between the amorphized and crystalline sapphire. When Mo is first implanted, the MoS2 crystals still predominantly appear at the amorphous-crystalline interface (which is much rougher), but they are much thicker, suggesting a different nucleation mechanism.

Ferroelectric Switching at Symmetry-Broken Interfaces by Local Control of Dislocations Networks.

Semiconducting ferroelectric materials with low energy polarization switching offer a platform for next-generation electronics such as ferroelectric field-effect transistors. Recently discovered interfacial ferroelectricity in bilayers of transition metal dichalcogenide films provides an opportunity to combine the potential of semiconducting ferroelectrics with the design flexibility of 2D material devices. Here, local control of ferroelectric domains in a marginally twisted WS2 bilayer is demonstrated with a scanning tunneling microscope at room temperature, and their observed reversible evolution is understood using a string-like model of the domain wall network (DWN). Two characteristic regimes of DWN evolution are identified: (i) elastic bending of partial screw dislocations separating smaller domains with twin stackings due to mutual sliding of monolayers at domain boundaries and (ii) merging of primary domain walls into perfect screw dislocations, which become the seeds for the recovery of the initial domain structure upon reversing electric field. These results open the possibility to achieve full control over atomically thin semiconducting ferroelectric domains using local electric fields, which is a critical step towards their technological use.

Interfacial Reconstructed Layer Controls the Orientation of Monolayer Transition-Metal Dichalcogenides.

Growing continuous monolayer films of transition-metal dichalcogenides (TMDs) without the disruption of grain boundaries is essential to realize the full potential of these materials for future electronics and optoelectronics, but it remains a formidable challenge. It is generally believed that controlling the TMDs orientations on epitaxial substrates stems from matching the atomic registry, symmetry, and penetrable van der Waals forces. Interfacial reconstruction within the exceedingly narrow substrate-epilayer gap has been anticipated. However, its role in the growth mechanism has not been intensively investigated. Here, we report the experimental conformation of an interfacial reconstructed (IR) layer within the substrate-epilayer gap. Such an IR layer profoundly impacts the orientations of nucleating TMDs domains and, thus, affects the materials' properties. These findings provide deeper insights into the buried interface that could have profound implications for the development of TMD-based electronics and optoelectronics.

Laser induced crystallization of sputtered MoS2 thin films

The integration of transition metal dichalcogenides (TMDs) thin films into Si CMOS-based devices requires the development of new bottom-up material growth approaches producing high crystallinity films without affecting the SiO2/Si substrate. For this purpose, sputtering is a suitable deposition method due to its simplicity, jointly with high reliability and large area deposition capabilities. However, sputtered layers are amorphous and require a post-deposition thermal treatment to obtain a highly crystalline film. Nanosecond pulsed laser annealing (PLA) has recently emerged as promising route to achieve large-scale crystalline TMDs films without significantly heating or affecting the underlying substrate. The aim of this work is to explore the possibility to produce crystalline 2H–MoS2 on large areas directly on a SiO2-on-Si substrate. The film structure, composition and morphology were monitored as a function of the laser pulse energy density by Raman spectroscopy, X-rays diffraction, Rutherford backscattered spectroscopy (RBS), scanning transmission electron microscopy (STEM) and atomic force microscopy (AFM). The electrical properties of the film with optimized crystallinity were finally investigated through deposition of Cr/Au contacts using shadow masks. This approach can be scaled to other TMDs materials and substrates, also paving the way for the fabrication of heterostructures and electrical devices on the top of a single substrate.

Self-hybridized exciton-polaritons in thin films of transition metal dichalcogenides for narrowband perfect absorption.

Monolayer direct-band gap transition metal dichalcogenides (TMDCs) have been extensively investigated in the context of light-matter interactions. To reach strong coupling, these studies make use of external optical cavities supporting well-defined resonant modes. However, use of an external cavity might limit the scope of possible applications of such systems. Here, we demonstrate that thin films of TMDCs can themselves serve as high-quality-factor cavities due to the guided optical modes they sustain in the visible and near-infrared ranges. Making use of the prism coupling, we achieve the strong coupling between excitons and guided-mode resonances lying below the light line, and show that the thickness of TMDC membranes can be used to tune and promote photon-exciton interactions within the strong-coupling regime. Additionally, we demonstrate narrowband perfect absorption in thin TMDC films through critical coupling with guided-mode resonances. Our work not only provides a simple and intuitive picture to tame interaction of light and matter in thin TMDC films, but also suggests that these simple systems are a promising platform for realizing polaritonic and optoelectronic devices.

Laser-Synthesized 2D-MoS2 Nanostructured Photoconductors.

The direct laser synthesis of periodically nanostructured 2D transition metal dichalcogenide (2D-TMD) films, from single source precursors, is presented here. Laser synthesis of MoS2 and WS2 tracks is achieved by localized thermal dissociation of Mo and W thiosalts, caused by the strong absorption of continuous wave (c.w.) visible laser radiation by the precursor film. Moreover, within a range of irradiation conditions we have observed occurrence of 1D and 2D spontaneous periodic modulation in the thickness of the laser-synthesized TMD films, which in some cases is so extreme that it results in the formation of isolated nanoribbons with a width of ~200 nm and a length of several micrometers. The formation of these nanostructures is attributed to the effect that is known as laser-induced periodic surface structures (LIPSS), which is caused by self-organized modulation of the incident laser intensity distribution due to optical feedback from surface roughness. We have fabricated two terminal photoconductive detectors based on nanostructured and continuous films and we show that the nanostructured TMD films exhibit enhanced photo-response, with photocurrent yield increased by three orders of magnitude as compared to their continuous counterparts.

Assembling a Photoactive 2D Puzzle: From Bulk Powder to Large-Area Films of Semiconducting Transition-Metal Dichalcogenide Nanosheets

ConspectusTwo-dimensional (2D) semiconducting materials are poised to revolutionize ultrathin, high-performance optoelectronic devices. In particular, transition-metal dichalcogenides (TMDs) are well-suited for applications requiring robust and stable materials such as electrocatalytic, photocatalytic, and photo-electrochemical devices. One of the most compelling assets of these materials is the ability to produce and process 2D TMDs in the nanosheet form using solution-based (SB) exfoliation methods. Compared to other methods, SB techniques are typically inexpensive, efficient, and more suitable for scale-up and industrial implementation. In acknowledgment of the importance of this area, much work has been done to develop various SB methods starting from the exfoliation of bulk crystalline TMD materials to the chemical modification of final devices consisting of thin films of semiconducting 2D TMD nanosheets. However, not all SB methods are equally compatible or interchangeable, and they result in very diverse material and device properties. Therefore, the aim of this Account is to provide an overview of the developed SB techniques that can serve as a guide for assembling high-performance thin films of 2D TMDs. We start by introducing the most popular methods for producing 2D TMDs using liquid-phase exfoliation (LPE), discussing their working mechanisms as well as their advantages and disadvantages. Notably we highlight a recently developed LPE technique using electro-intercalation that draws on the advantages of previously presented methods. Next, we discuss processing the as-produced 2D TMD nanosheets via SB separating techniques designed for size and morphology selection while also presenting the ongoing challenges in this area. We then examine SB methods for processing the selected 2D nanomaterial dispersions into semiconducting thin films. Various methods are compared and contrasted, and special attention is paid to a recently developed method that carefully deposits 2D TMD nanoflakes with preferential alignment and has been shown scalable to the meter-squared size range. Finally, we explore strategies for increasing the optoelectronic performance of the TMD films via device engineering and defect management. We scrutinize these post-treatments based on the final device application, which are explicitly discussed. In all of the discussed processes we present the most promising SB techniques giving critical analysis and insight from experience. While we provide our own “best practices”, we stress the use of adaptability and critical thinking when designing specifically tailored procedures. By providing examples of different uses and measured improvements in one comprehensive guide, we hope to simplify process-development and aid researchers in making their own unique photoactive 2D “puzzles”.