High-Performance p–n Junction Transition Metal Dichalcogenide Photovoltaic Cells Enabled by MoO_x Doping and Passivation

Abstract

Layered semiconducting transition metal dichalcogenides (TMDs) are promising materials for high-specific-power photovoltaics due to their excellent optoelectronic properties. However, in practice, contacts to TMDs have poor charge carrier selectivity, while imperfect surfaces cause recombination, leading to a low open-circuit voltage (V OC) and therefore limited power conversion efficiency (PCE) in TMD photovoltaics. Here, we simultaneously address these fundamental issues with a simple MoO x (x ≈ 3) surface charge-transfer doping and passivation method, applying it to multilayer tungsten disulfide (WS2) Schottky-junction solar cells with initially near-zero V OC. Doping and passivation turn these into lateral p–n junction photovoltaic cells with a record V OC of 681 mV under AM 1.5G illumination, the highest among all p–n junction TMD solar cells with a practical design. The enhanced V OC also leads to record PCE in ultrathin (<90 nm) WS2 photovoltaics. This easily scalable doping and passivation scheme is expected to enable further advances in TMD electronics and optoelectronics.

High-specific-power flexible transition metal dichalcogenide solar cells

“…On the right side of Fig. 3b (corresponds to the lower edge in the photocurrent map), due to the passivation effect of MoO x 24 , current generation goes beyond Gr and occurs up to the MoO x right edge. A similar spatial averaging phenomenon is also taking place on this side, resulting in a ~2-μm tail beyond the MoO x edge.…”

“…3a, b ). MoO x also passivates the top surface of the solar cell, specifically the trap states at the Gr–WSe 2 interface 24 . These lead to a higher open-circuit voltage ( V OC ) and short-circuit current density ( J SC ) in MoO x -capped WSe 2 solar cells (Supplementary Note 2 and Supplementary Fig.…”

“…b Photocurrent profile along the x axis shown in a , demonstrating that the Gr/MoO x –WSe 2 junction area accurately represents the active area of the solar cell. The misaligned MoO x is passivating the WSe 2 top surface 24 , leading to the current generation up to the edge of MoO x . The photocurrent tails beyond the edges of Gr and MoO x occur due to the finite laser spot size (~2 μm).…”

High-Efficiency WSe2 Photovoltaic Devices with Electron-Selective Contacts

“…Efficiency chart of vdW material-based PV devices. ,,− Only PCE values measured under one-sun AM1.5G illumination are included on the chart. Thicknesses of the utilized materials are indicated for each point.…”

Two-Dimensional Violet Phosphorus: A p-Type Semiconductor for (Opto)electronics

“…[1][2][3] Novel paradigms in both fundamental and applied research have been disclosed by the assembling of p-n junctions based on 2D materials. [4][5][6][7] Nevertheless, their degree of freedom is limited by the scarcity in intrinsic p-type atomically thin structures, lagging behind the 2D materials exhibiting n-type behavior. So far, only a few species have been successfully identified, such as α-MnS, GaSe, InSe, WSe2, GeSe, GeS, 2D tellurium and selenium.…”