A type-II NGyne/GaSe heterostructure with high carrier mobility and tunable electronic properties for photovoltaic application

Abstract

The two-dimensional heterostructures with type-II band alignment and super-high carrier mobility offer an updated perspective for photovoltaic devices. Here, based on the first-principles calculation, a novel vertical NGyne/GaSe heterostructure with an intrinsic type-II band alignment, super-high carrier mobility (104 cm2V-1s-1), and strong visible to ultraviolet light absorption (104~105 cm-1) is constructed. We investigate the electronic structure and the interfacial properties of the NGyne/GaSe heterostructure under electric field and strain. The band offsets and band gap of the NGyne/GaSe heterostructure can be regulated under applied vertical electric field and strain efficiently. Further study reveals that the photoelectric conversion efficiency of the NGyne/GaSe heterostructure is vastly improved under a negative electric field and reaches up to 25.09%. Meanwhile, near-free electron states are induced under a large applied electric field, leading to the NGyne/GaSe heterostructure transform from semiconductors to metal. Our results indicate that the NGyne/GaSe heterostructure will have extremely potential in optoelectronic devices, especially solar cells.

Carrier mobility and optical properties of a type-II GaSe/ZnS heterostructure as a photocatalyst: a first-principles study

“…The results were consistent with the previously reported theoretical values. 8,19,22,34 On the other hand, the structurally optimized monolayer ZnS also had a hexagonal structure with a lattice parameter of a = b = 3.87 Å. The calculated value of the optimized bond length between Zn and S was 2.23 Å, which was consistent with previous experiments.…”

“…The electron mobility for the GaSe monolayer along different transmission directions ( x and y ) was 805.42 cm 2 V −1 s −1 and 401.12 cm 2 V −1 s −1 , respectively, and the hole mobility was only 16.02 cm 2 V −1 s −1 and 46.27 cm 2 V −1 s −1 , consistent with previous reports. 8,19,22 The effective masses of holes calculated along different transmission directions ( x and y ) were 2.73 m 0 and 3.58 m 0 , respectively. The calculated values were 9–12 times those of the electrons, which was beneficial for reducing the recombination rate of electron–hole pairs.…”

“…To analyze the transfer and redistribution of interface electrons during the formation process of heterostructures, the planar average electron density difference (Dr) was accurately calculated using the following equation: 8,19,22 Dr(z) = r(z) ZnS/GaSe À r(z) ZnS À r(z) GaSe (4) where r(z) ZnS/GaSe , r(z) GaSe , and r(z) ZnS are the charge density of the GaSe/ZnS heterostructures, monolayer GaSe and monolayer ZnS, respectively. From Fig.…”

“…18 The advantages of a stable structure, high carrier mobility (410 3 cm 2 V À1 s À1 ) and batch production make it a promising photocatalytic material. [19][20][21][22] In 2017, Alharbi et al grew ZnS and GaSe thin films on glass substrates by physical vapor deposition (PVD) at a vacuum pressure of 10 À5 mbar. The experimental results showed that the formation of a GaSe/ZnS heterostructure reduced the band gap to 2.0 eV, lowered the carrier concentration, and significantly enhanced the inherent optical absorption capacity of ZnS.…”

Search for simple β-AIMIIIO2-type intrinsic ferroelectric semiconductors with simultaneous robust built-in electric field and full-spectrum absorption for superior photocatalysts

“…The calculations showed that the electron mobility of these four β-AMO 2 candidate IFSs was in the range of 9 × 10 3 to 3.7 × 10 5 cm s −1 V −1 and the hole mobility was up to 1.7 × 10 3 cm s −1 V −1 compared with other types of photocatalysts, such as inorganic chalcogenides (9 × 10 2 –10 3 cm s −1 V −1 ), 82 inorganic–organic chalcogenides (7–30 × 10 3 cm s −1 V −1 ), 83 and heterojunction structures (104 cm s −1 V −1 ), 84 indicating the excellent catalytic performance of these ferroelectric photocatalysts.…”