Defect Engineering in Ultrathin SnSe Nanosheets for High-Performance Optoelectronic Applications

Abstract

Ultrathin lamellar SnSe is highly attractive for applications in areas such as photonics, photodetectors, photovoltaic devices, and photocatalysis, owing to its suitable band gap, exceptional light absorption capabilities, and considerable carrier mobility. On the other hand, SnSe nanosheets (NSs) still face challenges of being difficult to prepare and their devices having low photoelectric conversion efficiencies. Herein, ultrathin SnSe NSs with controlled Se defects were synthesized with high yield by a facial Li intercalation-assisted liquid exfoliation method. The loss of Se, a narrowing of the band gap, and an increase in lattice disorders involving vacancies, distortions, and phase transition were observed in SnSe NSs prepared with a long lithiation process. Comparing between the 24 and 72 h lithiation samples, the ones processed for a longer time displayed a faster recombination time due to more defect-induced mid-states. Inspiringly, enhancements of 4−10 times were observed for photodetector device parameters such as photocurrent, photoresponsivity, photoresponse speed, and specific detectivity of the 72 h lithiation SnSe NSs. Additionally, these devices show good stability and a broad detection range, from ultraviolet to the near infrared region. Our results provide a promising avenue for the mass production of SnSe NSs with high photoelectric performance and open up opportunities for applications in photonics, optoelectronics, and photocatalysis.

Tin Oxide (SnO2) Nanoparticles: Facile Fabrication, Characterization, and Application in UV Photodetectors

“…The response time (t res ) and recovery time (t rec ) are usually assigned to the time interval for the rise and decay from 10% to 90% and from 90% to 10% of the peak value, respectively [40]. It can be seen in Figure 4b and Figure S2 that the t res /t rec of the as-fabricated SnO 2 -NP-1-based electrode was 2.7 s/3.8 s, close to those of the SnO 2 -NP-2-based electrode (3.6 s/3.9 s) and the SnO 2 -NP-3-based electrode (3.5 s/3.8 s), all of which are comparable to those of SnSe nanosheets (1.2 s/2.2 s) [43] and bismuth selenide nanosheets (5.3 s/9.5 s) [44].…”

Recent Advances in SnSe Nanostructures beyond Thermoelectricity

“…The enhanced photoelectric performance of SnSe NSs is primarily ascribed to the narrowed band gap caused by the Se vacancies as well as vacancy‐assisted separation and recombination of the photogenerated carriers. [ 224 ]…”

“…The enhanced photoelectric performance of SnSe NSs is primarily ascribed to the narrowed band gap caused by the Se vacancies as well as vacancy-assisted separation and recombination of the photogenerated carriers. [224] The light absorption coefficient of SnSe decreases slowly with the increasing light wavelength due to its indirect band gap, which has achieved its advantage in near-infrared detection and even in detecting light far beyond its band gap; however, the indirect band gap also determines the low photoelectric conversion efficiency of SnSe. Table 10 lists the performance comparison of various SnSe-based photodetectors.…”

“…Finally, the simulation results showed that the π-SnSe also has prospective applications in optoelectronics, [95,225] which requires further exploration. [224] Copyright 2021, American Chemical Society.…”

Anisotropic to Isotropic Transition in Monolayer Group-IV Tellurides

“…In particular, group IV-VI semiconductors with layered structures and weak van der Waals interlayer interactions allowing for isolation by mechanical exfoliation have been considered as free-standing monolayers [11][12][13][14][15][16][17]. In addition, various two-dimensional nanosheets have already been successfully synthesized using chemical vapor deposition, liquid phase exfoliation, and spark plasma sintering techniques, rendering them potentially useful candidates for large-scale manufacturing and device applications [18][19][20][21][22][23][24][25][26][27].…”