High Photovoltaic Quantum Efficiency in Ultrathin van der Waals Heterostructures

Abstract

We report experimental measurements for ultrathin (<15 nm) van der Waals heterostructures exhibiting external quantum efficiencies exceeding 50% and show that these structures can achieve experimental absorbance >90%. By coupling electromagnetic simulations and experimental measurements, we show that pn WSe/MoS heterojunctions with vertical carrier collection can have internal photocarrier collection efficiencies exceeding 70%.

High‐Performance Photodiode Based on Atomically Thin WSe2/MoS2 Nanoscroll Integration

“…The EQE shows a decreasing trend generally with the reduction of the incident photon energy; however, apophysis appears when the incident photon energy is less than 1.77 eV, which arises from the excitonic edges of MoS 2 nanoscroll and WSe 2 according to the PL peak shown in Figure S5b in the Supporting Information. This result agrees with the reported absorption spectrum of MoS 2 /WSe 2 heterostructure in the previous reports . Lastly, the spectral responsivity dependent on incident power intensity is investigated and shown in Figure d, in which for every excitation wavelength, the R decreases with the increase of power intensity, which is similar to other 2D‐based photodetectors .…”

Two-Dimensional Material Molybdenum Disulfides as Electrocatalysts for Hydrogen Evolution

“…Fabricating TMDs/metal heterostructures is an effective way to further enhance their light absorption due to an increase in the local density of states (LDOS) near the semiconductor/metal interface [79][80][81]. The high light absorption combined with the active electrocatalytic performance make the semiconducting TMDs an excellent photoelectrocatalyst [78][79][80][81]. Lewis's group investigated the photoelectrochemical performance of Pt-decorated p-type WSe2 photocathodes by using scanning photocurrent microscopy [78].…”

“…The semiconducting TMDs have an indirect band gap of 1.0 eV to 1.5 eV, and a direct band gap of 1.4 eV to 2.3 eV [78][79][80][81][82]. When the photon energies are above the indirect and direct band gap, the TMDs will absorb the photon and show large absorption coefficients (≈10 5 cm −1 and ≈10 6 cm −1 , respectively) [78][79][80][81][82]. For example, the WSe 2 material shows high absorption with near-unity absorption peak occurring between 500 and 650 nm [79].…”

“…For example, the WSe 2 material shows high absorption with near-unity absorption peak occurring between 500 and 650 nm [79]. Fabricating TMDs/metal heterostructures is an effective way to further enhance their light absorption due to an increase in the local density of states (LDOS) near the semiconductor/metal interface [79][80][81]. The high light absorption combined with the active electrocatalytic performance make the semiconducting TMDs an excellent photoelectrocatalyst [78][79][80][81].…”

Recent Progress on Two‐Dimensional Heterostructures for Catalytic, Optoelectronic, and Energy Applications

“…It should be noted that the charge separation is key concept of the applications of 2D materials on solar cells. After that, Wong et al [124] reported that the absorbance of ultrathin MoS 2 /WSe 2 vdW heterostructure was higher than 90 %. The schematic, SEM, and electronic band diagram of the WSe 2 / MoS 2 lateral heterostructures solar cells is shown in Figure 6b, where a highly power conversion efficiency of 2.56 % (Figure 6c), which was the highest efficiency of broadband/sun source illumination reported in 2D monolayer lateral heterostructures at that time, was realized.…”