Out-of-plane polarization induces a picosecond photoresponse in rhombohedral stacked bilayer WSe₂

• Guixian Liu,
• Yufan Wang,
• Zhoujuan Xu,
• Zhouxiaosong Zeng,
• Lanyu Huang,
• Cuihuan Ge and
• Xiao Wang

Beilstein J. Nanotechnol. 2024, 15, 1362–1368, doi:10.3762/bjnano.15.109

• and the scanning photocurrent map under zero bias, we reveal a non-zero short-circuit current in the graphene/3R WSe2/graphene heterojunction region, demonstrating the bulk photovoltaic effect. Furthermore, the out-of-plane polarization enables the 3R WSe2 heterojunction region to achieve an ultrafast

• photodetectors. Keywords: broken inversion symmetry; out-of-plane polarization; picosecond photoresponse; time-resolved photocurrent measurement (TRPC); WSe2; Introduction Two-dimensional (2D) van der Waals (vdW) ferroelectrics with dangling-bond-free surfaces exhibit ferroelectricity by effectively resisting

• polarization, offering promising advances in optoelectronics [23][30]. One of the key optoelectronic phenomena in 2D semiconductor materials is the photocurrent response. The polarization, which results in spontaneous photocurrent under zero bias, gives rise to the bulk photovoltaic effect (BPVE), which can

Photocatalytic methane oxidation over a TiO₂/SiNWs p–n junction catalyst at room temperature

• Qui Thanh Hoai Ta,
• Luan Minh Nguyen,
• Ngoc Hoi Nguyen,
• Phan Khanh Thinh Nguyen and
• Dai Hai Nguyen

Beilstein J. Nanotechnol. 2024, 15, 1132–1141, doi:10.3762/bjnano.15.92

• Information File 1, Figure S2. The contact angle between horizontal sample surface and the perimeter of the water drop was measured after 10 s of interaction. The in situ photocurrent measurements were carried out in the presence of gaseous reactants (CH4/air = 4.5/0.5) ranging from −2 V to +3 V under dark

Directed growth of quinacridone chains on the vicinal Ag(35 1 1) surface

• Niklas Humberg,
• Lukas Grönwoldt and
• Moritz Sokolowski

Beilstein J. Nanotechnol. 2024, 15, 556–568, doi:10.3762/bjnano.15.48

• found a hole mobility of 0.1 cm2·V−1·s−1 and a photocurrent of about 1 mA·cm−2. These observations were both attributed to a close packing of the molecules due to strong intermolecular H-bonds. The empirical formula of QA is C20H12N2O2, and a structural formula and a hard-sphere model of QA are

CdSe/ZnS quantum dots as a booster in the active layer of distributed ternary organic photovoltaics

• Gabriela Lewińska,
• Piotr Jeleń,
• Zofia Kucia,
• Maciej Sitarz,
• Łukasz Walczak,
• Bartłomiej Szafraniak,
• Jerzy Sanetra and
• Konstanty W. Marszalek

Beilstein J. Nanotechnol. 2024, 15, 144–156, doi:10.3762/bjnano.15.14

• equal to or greater than the binding energy of singlet and triplet excitons. The energy levels system of the considered devices with QDs determines the optimal photocurrent of dissociation for most singlet excitons, which require at least 0.07 eV energy [64]. The production of charge-transfer carrier

Properties of tin oxide films grown by atomic layer deposition from tin tetraiodide and ozone

• Kristjan Kalam,
• Peeter Ritslaid,
• Tanel Käämbre,
• Aile Tamm and
• Kaupo Kukli

Beilstein J. Nanotechnol. 2023, 14, 1085–1092, doi:10.3762/bjnano.14.89

• photocurrent and normalising the signal to a reference photocurrent signal from a clean gold mesh located behind the last optical element of the beamline. Results and Discussion To establish the evaporator temperature that provides the maximum coverage of substrate surface with precursor molecules and

A visible-light photodetector based on heterojunctions between CuO nanoparticles and ZnO nanorods

• Doan Nhat Giang,
• Nhat Minh Nguyen,
• Duc Anh Ngo,
• Thanh Trang Tran,
• Le Thai Duy,
• Cong Khanh Tran,
• Thi Thanh Van Tran,
• Phan Phuong Ha La and
• Vinh Quang Dang

Beilstein J. Nanotechnol. 2023, 14, 1018–1027, doi:10.3762/bjnano.14.84

• , including 395 nm (purple), 465 nm (blue), 532 nm (green), and 640 nm (red). Our device exhibited a high photocurrent of 10.4 μA and good responsivity (1.38 A·W−1) at 2 V bias. Although this is a fundamental study, it highlights the potential of the CuO/ZnO heterostructure for visible-light photodetectors

• relations under reverse and bias voltages, indicating a good ohmic contact between semiconductor materials and Ag electrodes [42]. It is worth noting that the current rise corresponds to the light intensity increase. The highest photocurrent reached 18 μA under a light illumination of 1.28 mW·cm−2. The low

• 0.7 μA, approximately the dark current, which shows the excellent recovery ability of the device. The time-dependent photoresponse at a constant bias of 2 V under 30 s illumination with 395 nm light at different intensities is presented in Figure 3b. When the light is turned on, the photocurrent

Photoelectrochemical water oxidation over TiO₂ nanotubes modified with MoS₂ and g-C₃N₄

• Phuong Hoang Nguyen,
• Thi Minh Cao,
• Tho Truong Nguyen,
• Hien Duy Tong and
• Viet Van Pham

Beilstein J. Nanotechnol. 2022, 13, 1541–1550, doi:10.3762/bjnano.13.127

• , TNAs, g-C3N4, and MoS2, of 226, 767, and 154 mV/dec, respectively. After the modification, the Tafel slope value of g-C3N4/TNAs is only about 137 mV/dec, while the best Tafel slope value of MoS2/TNAs is only 113 mV/dec. Furthermore, the photocurrent of the materials was evaluated through the assessment

• light, which can be explained as follows: The photocurrent density of MoS2/TNAs promptly increased because of the efficient separation of the e−–h+ pairs at the interfaces between TNAs and MoS2 [58] and the rapid transfer of the photo-induced electrons from MoS2 to the TNAs electrode [59]. This result

• g-C3N4/TNAs and MoS2/TNAs heterojunctions achieved about 139.6 and 210.6 µA/cm2. In addition, the PEC reaction rate was evaluated by the Tafel slope value, indicating a faster rate for the MoS2/TNAs heterojunction compared to the g-C3N4/TNAs heterojunction. Moreover, the photocurrent density of MoS2

A TiO₂@MWCNTs nanocomposite photoanode for solar-driven water splitting

• Anh Quynh Huu Le,
• Ngoc Nhu Thi Nguyen,
• Hai Duy Tran,
• Van-Huy Nguyen and
• Le-Hai Tran

Beilstein J. Nanotechnol. 2022, 13, 1520–1530, doi:10.3762/bjnano.13.125

• KOH concentration higher than 3 M insignificantly affects the activation voltage of the TiO2@MWCNTs photoelectrochemical electrode. The increase in KOH concentration could improve the electrical conductivity and the photocurrent of the photoelectrochemical electrode [44][45]. As seen in Figure 9b, the

LED-light-activated photocatalytic performance of metal-free carbon-modified hexagonal boron nitride towards degradation of methylene blue and phenol

• Nirmalendu S. Mishra and
• Pichiah Saravanan

Beilstein J. Nanotechnol. 2022, 13, 1380–1392, doi:10.3762/bjnano.13.114

• , lower charge transfer resistance, and improved charge carrier density (2.97 × 1019 cm−3). This subsequently enhanced the photocurrent density (three times) and decreased the photovoltage decay time (two times) in comparison to those of HBN. The electronic band structure (obtained through Mott–Schottky

Near-infrared photoactive Ag-Zn-Ga-S-Se quantum dots for high-performance quantum dot-sensitized solar cells

• Roopakala Kottayi,
• Ilangovan Veerappan and
• Ramadasse Sittaramane

Beilstein J. Nanotechnol. 2022, 13, 1337–1344, doi:10.3762/bjnano.13.110

• measured by using an AM 1.5 solar simulator (Oriel instruments 67005) of 100 mW·cm−2 power density. This power density was calibrated with the photocurrent of the reference cell (crystal Si capped by an IR cut filter). Fill factor (FF) and photoconversion efficiency (η) were calculated by using the

• efficient photoanode for QDSCs and it produces more electron–hole pairs, which helps to improve the photocurrent density. Time-resolved photoluminescence (TRPL) studies were carried out to evaluate the electrons decay time of AZGSSe/TiO2. The decay curve was fitted with a biexponential function [33] and it

Recent trends in Bi-based nanomaterials: challenges, fabrication, enhancement techniques, and environmental applications

• Vishal Dutta,
• Ankush Chauhan,
• Ritesh Verma,
• C. Gopalkrishnan and
• Van-Huy Nguyen

Beilstein J. Nanotechnol. 2022, 13, 1316–1336, doi:10.3762/bjnano.13.109

• (λ > 420 nm), photoelectrochemical studies demonstrated that the RhB photodegradation effectiveness and photocurrent density of the BiIO4/Bi2MoO6 hybrid composite is much higher than that of the pure components. Because of the successful construction of the BiIO4/Bi2MoO6 hybrid, the photocatalytic

• , is more sensitive to photocurrent, and has a lower electrochemical impedance rate. This is because of surface plasmon resonances (SPRs) and the electron transport capabilities of Bi. The photocatalytic activity for the breakdown of phenol was significantly improved, compared to pristine Bi2WO6 under

Spindle-like MIL101(Fe) decorated with Bi₂O₃ nanoparticles for enhanced degradation of chlortetracycline under visible-light irradiation

• Chen-chen Hao,
• Fang-yan Chen,
• Kun Bian,
• Yu-bin Tang and
• Wei-long Shi

Beilstein J. Nanotechnol. 2022, 13, 1038–1050, doi:10.3762/bjnano.13.91

• ) with BaSO4 as a reference. The photoluminescence spectrum (PL) was obtained from a luminescence spectrometer at an excitation wavelength of 446 nm (RF-530IPC, Shimadzu, Japan). The photocurrent response and electrochemical impedance spectra (EIS) were measured by an electrochemical workstation

• further elucidate the transfer behavior of the charge carriers in BOM-20, photocurrent responses were carried out under visible light (λ > 420 nm) and were displayed in Figure 5c. The photocurrent density of the BOM-20 composite is significantly higher than that of pristine Bi2O3 and MIL101(Fe), which

• possesses the lowest resistance and the highest separation rate of electron–hole pairs on the interface of MIL101(Fe) and Bi2O3 [57], which is consistent with the results from PL spectra and photocurrent analysis. In summary, PL spectra, photocurrent responses, and EIS analysis all indicated that Bi2O3

Hierarchical Bi₂WO₆/TiO₂-nanotube composites derived from natural cellulose for visible-light photocatalytic treatment of pollutants

• Zehao Lin,
• Zhan Yang and
• Jianguo Huang

Beilstein J. Nanotechnol. 2022, 13, 745–762, doi:10.3762/bjnano.13.66

• , respectively. The transient photocurrent responses and electrochemical impedance spectroscopy (EIS) Nyquist plots (frequency: 0.01 Hz−100 kHz, alternate current: 5 mV) of a given sample were obtained on a CHI 760D (Shanghai, China) electrochemical workstation using a three-electrode system. The Pt plate (1.0

• photogenerated electron−hole pairs. It is reported that the transient photocurrent responses of the samples depend on the amounts of photogenerated charges and the kinetics of charge separation of the corresponding electrodes under irradiation of light [62]. As shown in Figure 10a, under irradiation of visible

• light (λ > 420 nm) at intervals of 30 s, all the Bi2WO6/TiO2-NT nanocomposites exhibit higher photocurrent responses than that of the pure Bi2WO6 powder sample except for the 30%−Bi2WO6/TiO2-NT nanocomposite, revealing that the recombination of photoinduced electrons and holes is inhibited on the

Direct measurement of surface photovoltage by AC bias Kelvin probe force microscopy

• Masato Miyazaki,
• Yasuhiro Sugawara and
• Yan Jun Li

Beilstein J. Nanotechnol. 2022, 13, 712–720, doi:10.3762/bjnano.13.63

• influence of the photocurrent [35][36][37]. The ultraviolet (UV) light source was a He–Cd laser (Kimmon Koha) with a wavelength of 325 nm and a laser power of 2 mW. A lens was equipped on a xyz-scanner in the UHV chamber to focus the laser onto the sample with a beam diameter of 500 µm. A band-pass filter

Influence of thickness and morphology of MoS₂ on the performance of counter electrodes in dye-sensitized solar cells

• Lam Thuy Thi Mai,
• Hai Viet Le,
• Ngan Kim Thi Nguyen,
• Van La Tran Pham,
• Thu Anh Thi Nguyen,
• Nguyen Thanh Le Huynh and
• Hoang Thai Nguyen

Beilstein J. Nanotechnol. 2022, 13, 528–537, doi:10.3762/bjnano.13.44

• DSSC using MoS2-1.25/FTO CE displayed an excellent photovoltaic performance compared to that with a Pt/FTO a CE. In particular, the obtained value of 16.3 mA·cm−2 for the short-circuit photocurrent (Jsc) was found to be higher than that of Pt/FTO CE (15.3 mA·cm−2). This is attributed to the high number

• Na2S of 5/30). In addition, as-prepared MoS2 films have been used as an alternative CE to Pt in DSSCs. The short-circuit photocurrent (Jsc) was higher than that of a Pt/FTO CE. Moreover, the highest performance of solar cells was found with the layered MoS2 film thank to good electrical conductivity, a

• -Newport-USA, Model No. 94061A). Simulated sunlight of 100 mW·cm−2 (1 sun) was generated and corrected by a 1000 W Xe lamp and an AM 1.5 filter. The photocurrent density–voltage (J–V) curves of the DSSCs were measured using a Keithley model 2400 multisource meter. Electrochemical impedance spectroscopy

Impact of device design on the electronic and optoelectronic properties of integrated Ru-terpyridine complexes

• Max Mennicken,
• Sophia Katharina Peter,
• Corinna Kaulen,
• Ulrich Simon and
• Silvia Karthäuser

Beilstein J. Nanotechnol. 2022, 13, 219–229, doi:10.3762/bjnano.13.16

• increases linearly with the intensity of the irradiating light, while they exhibit on/off ratios of less than 1.01 for light intensities of 1 µW/cm2. We find an increase of the photocurrent through the Ru(MPTP)2–AuNP devices due to irradiation above a threshold voltage of about 0.4 to 0.5 V (Figure 6a

Tin dioxide nanomaterial-based photocatalysts for nitrogen oxide oxidation: a review

• Viet Van Pham,
• Hong-Huy Tran,
• Thao Kim Truong and
• Thi Minh Cao

Beilstein J. Nanotechnol. 2022, 13, 96–113, doi:10.3762/bjnano.13.7

• extending the light harvesting range and promoting the separation of photogenerated electrons. A considerable amount of reactive oxygen radicals was produced during the photocatalytic reaction, resulting from the large amount of free surface OH groups. PL, photocurrent response, electrochemical impedance

• generation architectural structure of heterojunctions toward visible-light-driven NO degradation”, article no. 117510, Copyright (2021), with permission from Elsevier. This content is not subject to CC BY 4.0. (a) Surface photovoltage spectroscopy, (b) transient photocurrent responses, (c) EIS Nyquist plots

• . (c) Transient photocurrent response and (d) EIS curves of SnO2 and SnO2/GQDs (1%) under visible light illumination and in darkness. Figure 13 was reprinted from [36], Applied Surface Science, vol. 448, by Xie, Y.; Yu, S.; Zhong, Y.; Zhang, Q.; Zhou, Y. “SnO2/graphene quantum dots composited

A Au/CuNiCoS₄/p-Si photodiode: electrical and morphological characterization

• Adem Koçyiğit,
• Adem Sarılmaz,
• Teoman Öztürk,
• Faruk Ozel and
• Murat Yıldırım

Beilstein J. Nanotechnol. 2021, 12, 984–994, doi:10.3762/bjnano.12.74

• values with increasing illumination power density due to enhancing number of charge carriers at the interface at reverse biases. A photocurrent value 1000 times higher than the dark current was obtained, owing to the existence of the interfacial CuNiCoS4 layer and the semiconductor p-Si [21][22]. The

• in Table 1. The F(V)–V plots represent normal Norde function plots, and the F(V) values decreased with increasing light power, especially in the low-voltage region due to the increasing photocurrent. The obtained values of ϕb and Rs are in good agreement with the ϕb and Rs values derived from

• various organic interlayers [33][34]. The graphs of log I and photoresponsivity as functions of log P of the Au/CuNiCoS4/p-Si are given in Figure 8. The photoconducting behavior of the diodes is described by the relation I = BPm, where I is the photocurrent, B is a constant, P is the illumination

Nanoporous and nonporous conjugated donor–acceptor polymer semiconductors for photocatalytic hydrogen production

• Zhao-Qi Sheng,
• Yu-Qin Xing,
• Yan Chen,
• Guang Zhang,
• Shi-Yong Liu and
• Long Chen

Beilstein J. Nanotechnol. 2021, 12, 607–623, doi:10.3762/bjnano.12.50

• ) and triazine (A2) fragments. The photocatalytic activities of CPs with different D/A1 ratios were systematically investigated and compared. For example, P8 (D/A1 = 3:7) (Figure 2) yielded the highest HER (966 μmol·h−1, 50 mg), which was consistent with the highest photocurrent response, smallest

Impact of GaAs(100) surface preparation on EQE of AZO/Al₂O₃/p-GaAs photovoltaic structures

• Piotr Caban,
• Rafał Pietruszka,
• Jarosław Kaszewski,
• Monika Ożga,
• Bartłomiej S. Witkowski,
• Krzysztof Kopalko,
• Piotr Kuźmiuk,
• Katarzyna Gwóźdź,
• Ewa Płaczek-Popko,
• Krystyna Lawniczak-Jablonska and
• Marek Godlewski

Beilstein J. Nanotechnol. 2021, 12, 578–592, doi:10.3762/bjnano.12.48

• results from the existence of a barrier for the photocurrent, which is effective for a high current density when the sample is illuminated by the solar spectrum. However, a small current density of the quantum efficiency measurement is able to pass the barrier [56]. Another possible reason for the above

Boosting of photocatalytic hydrogen evolution via chlorine doping of polymeric carbon nitride

• Malgorzata Aleksandrzak,
• Michalina Kijaczko,
• Wojciech Kukulka,
• Daria Baranowska,
• Martyna Baca,
• Beata Zielinska and
• Ewa Mijowska

Beilstein J. Nanotechnol. 2021, 12, 473–484, doi:10.3762/bjnano.12.38

• . Figure 9a shows the transient photocurrent response of PCN and Cl-PCN. One can observe two-fold enhancement of the photocurrent response after chlorine doping of PCN. It demonstrates an improved generation of electron–hole pairs and better transportation of the charge carriers after modification. After

• . It further indicates that Cl doping can promote transfer and separation of the photogenerated carriers [55], which agrees with the photoluminescence spectroscopy results and transient photocurrent response. The improved transport and separation can be affected by Cl atoms acting as a charge carrier

• layers. Although Cl doping did not affect the reduction in the bandgap energy, the transient photocurrent response of Cl-PCN was enhanced compared to pristine PCN, indicating a better transport and separation of the photoinduced charges. It indicates that a higher amount of electrons can migrate to the

Absorption and photoconductivity spectra of amorphous multilayer structures

• Oxana Iaseniuc and
• Mihail Iovu

Beilstein J. Nanotechnol. 2020, 11, 1757–1763, doi:10.3762/bjnano.11.158

• of the photocurrent spectra is attributed to the different values of the optical bandgap of the involved amorphous layers (Eg ≈ 2.0 eV for As0.40S0.30Se0.30 and Ge0.09As0.09Se0.82 and Eg ≈ 3.0 eV for Ge0.30As0.04S0.66). The obtained experimental results are discussed taking into account the light

• ; photocurrent; transmission spectra; Introduction The As–S–Se, Ge–As–Se, and Ge–As–S ternary glass systems currently attract a lot of attention because of their wide application in IR optics, non-linear optics, photonics, optoelectronics, and as recording media for holography and e-beam lithography [1][2][3

• ]. The physical properties of covalently bonded glasses are determined by the mean coordination number Z (average number of covalent bonds per atom) [4]. It is well known that the functionality of many photonic and optoelectronic devices is based on the intrinsic photoelectric effect. The photocurrent

High-responsivity hybrid α-Ag₂S/Si photodetector prepared by pulsed laser ablation in liquid

• Raid A. Ismail,
• Hanan A. Rawdhan and
• Duha S. Ahmed

Beilstein J. Nanotechnol. 2020, 11, 1596–1607, doi:10.3762/bjnano.11.142

• decrease in the electrical resistivity of Ag2S. Figure 12 illustrates the I–V characteristics under illumination of the heterojunctions at reverse bias. The photocurrent of the heterojunction increased from 460 to 1500 μA at 7.5 V after CTAB was added to the Tu solution. This result can be ascribed to the

• figures of merit of the photodetector and it can be defined as the ratio of photocurrent Iph to the incident light power Ps as shown in the following equation: Figure 13 shows the spectral responsivity (Rλ) of Ag2S prepared in the Tu solutions with and without the CTAB surfactant. We observed a response

• . The energy band diagram under illumination of the n-Ag2S NPs/p-Si heterojunction prepared in pure Tu is shown in Figure 14. The electron affinity of Ag2S required for the band line-up construction was obtained from reported data [50]. As shown in Figure 12, the photocurrent in the photodetector came

Excitonic and electronic transitions in Me–Sb₂Se₃ structures

• Nicolae N. Syrbu,
• Victor V. Zalamai,
• Ivan G. Stamov and
• Stepan I. Beril

Beilstein J. Nanotechnol. 2020, 11, 1045–1053, doi:10.3762/bjnano.11.89

• that is characteristic of the conductivity hopping mechanism which in turn is independent of the metal type and the deposition method used. The photocurrent increases when the energy of the photons increases in the Schottky barriers when the transparent contacts are illuminated. The structures with the

• contacts deposited onto one side of the crystal are photosensitive. At the same time, the contact deposition onto opposite sides of the crystal planes leads to the appearance of a photo-electromotive force (EMF) with a magnitude of up to 150 mV. The photocurrent increases when a positive voltage is applied

• minimum region. It is highly likely that the photoconductivity maxima are due to excitonic ground states (n = 1) in the aforementioned polarization conditions. In addition, the photocurrent increases when the bias increases. For the unpolarized light case, the photoconductivity spectra have a narrow

A new photodetector structure based on graphene nanomeshes: an ab initio study

• Babak Sakkaki,
• Hassan Rasooli Saghai,
• Ghafar Darvish and
• Mehdi Khatir

Beilstein J. Nanotechnol. 2020, 11, 1036–1044, doi:10.3762/bjnano.11.88

• , and then proceed with the design of the photodetector based on a suitable material. We further calculate the transport and photocurrent of the devices. To demonstrate improved performance of the proposed devices, we perform simulations on three types of devices. Graphene, GNMs and GNRs are materials

• permittivity and system volume, respectively. The relative dielectric constant, εr, is related to the susceptibility, χ, as [26][27]: The photocurrent is calculated by first-order perturbation theory in the framework of the Born approximation. In short, light–electron interaction is added to the Hamiltonian as

• materials using optical analysis. Finally, by calculating the photocurrent of the detectors based on these materials, we discuss the benefits of using them as infrared detectors. Armchair graphene nanoribbons (AGNRs) are often classified into three families, namely 3m, 3m + 1, and 3m + 2 (m is a positive