Large-Area, High-Specific-Power Schottky-Junction Photovoltaics from CVD-Grown Monolayer MoS₂

Abstract

The deployment of two-dimensional (2D) materials for solar energy conversion requires scalable large-area devices. Here, we present the design, modeling, fabrication, and characterization of monolayer MoS 2 -based lateral Schottky-junction photovoltaic (PV) devices grown by using chemical vapor deposition (CVD). The device design consists of asymmetric Ti and Pt metal contacts with a work function offset to enable charge separation. These early stage devices show repeatable performance under 1 sun illumination, with V OC of 160 mV, J SC of 0.01 mA/cm 2 , power conversion efficiency of 0.0005%, and specific power of 1.58 kW/kg. An optoelectronic model for this device is developed and validated with experimental results. This model is used to understand loss mechanisms and project optimized device designs. The model predicts that a 2D PV device with ∼70 kW/kg of specific power can be achieved with minimum optimization to the current devices. By increasing the thickness of the absorber layer, we can achieve even higher performance devices. Finally, a 25 mm 2 area solar cell made with a 0.65 nm thick MoS 2 monolayer is demonstrated, showing V OC of 210 mV under 1 sun illumination. This is the first demonstration of a large-area PV device made with CVD-grown scalable 2D materials.

High‐Performance and Lithography‐Free Au/WS2/Ag Vertical Schottky Junction Solar Cells

“…The exponential increase of J with respect to V is evident from the linear relationship between log|J| and V (Figure S4a, Supporting Information). Based on the thermionic emission law, [12][13][14][15]34] the Schottky barrier height (SBH) and ideality factor (n) of the Au/WS 2 /Ag device were estimated to be 240 meV and 1.73, respectively (Figure S4a, Supporting Information). Murali et al estimated the SBH of 270 (or 290) meV at Au/WS 2 interface with WS 2 flakes with thicknesses of 40-60 nm, [19] which is very similar to the SBH estimated from our device.…”

“…[12,15] However, the measured J SC of TMD-based solar cells is considerably lower than the value predicted from the optical absorption in the active layers. [8][9][10][11][12][13][14][15] Even though TMD heterostructures are composed of identical materials with similar thicknesses, the V OC and J SC values reported in the literature vary significantly. [9] In most cases, TMD heterostructures are fabricated by stacking randomly shaped, small-sized exfoliated flakes.…”

Type-II MoSi2N4/MoS2 van der Waals Heterostructure with Excellent Optoelectronic Performance and Tunable Electronic Properties

“…Since the first exfoliation in 2004, graphene has attracted great research interest due to its unique linear band dispersion relationship, , the quantum Hall effect at room temperature, , and the high carrier mobility. , However, perfect graphene is a zero-gap semimetal, limiting its application in electronic devices. , Hence, in order to overcome the limitations of graphene, two-dimensional (2D) transition metal dichalcogenides (TMDs) − have attracted widespread attention due to their semiconductivity and other premium properties for nanoelectronic applications. − In particular, the MoS 2 monolayer is a semiconductor with a direct band gap of 1.8 eV and this value lies in the visible light range, offering significant advantages in many applications such as field-effect transistors, , high-performance electrocatalysts, , and photovoltaic devices. , …”

“…13−16 In particular, the MoS 2 monolayer is a semiconductor with a direct band gap of 1.8 eV and this value lies in the visible light range, offering significant advantages in many applications such as field-effect transistors, 17,18 high-performance electrocatalysts, 19,20 and photovoltaic devices. 21,22 In recent years, vertical stacking of different 2D materials to form van der Waals heterostructures (vdWHs) provides additional opportunities to meet the needs of various nanodevice applications. 23−28 In general, vdWHs with type-II energy band alignment are most commonly used in optoelectronic devices due to their ability to efficiently separate photogenerated electrons and holes.…”

Piezoelectricity-modulated optical recombination dynamics of monolayer-MoS2/GaN-film heterostructures

“…3 Furthermore, a direct bandgap of ∼1.85 eV, which lies in the spectral range of visible light, endows monolayer MoS 2 with intriguing optical properties. [4][5][6][7][8] A broad range of ultrathin MoS 2 optoelectronics have been developed, including photodetectors, [9][10][11][12][13][14][15] photovoltaics, [16][17][18][19] LEDs, [20][21][22][23][24] and photoelectrochemical cells. 25,26 Monolayer MoS 2 features a hexagonal crystal structure and it is non-centrosymmetric, thus demonstrating strong piezoelectricity along the e 11 direction.…”