Transport Of Photogenerated Carriers Research Articles

Piezoelectric effect achieves efficient carriers’ spatial separation and enhanced photocatalytic H2 evolution of UiO-66-NH2@CdS by transforming charge transfer mechanism

The internal electric field induced by piezoelectric effect can optimize the transport pathway of photogenerated charge in photocatalysis. We constructed an effcient piezoelectric photocatalytic heterojunction UiO-66-NH2@CdS and achieved a shift in the charge transfer mechanism through the piezoelectric effect, resulting in excellent photocatalytic H2 evolution performance. The optimal heterojunction under the ultrasonic environment exhibited 2028.48 μmol·g−1·h−1 photocatalytic H2 evolution performance, roughly four times better than no-ultrasound condition. Because of the piezoelectric polarization of UiO-66-NH2, the photogenerated carrier transport mechanism was changed from type Ⅱ to the more favorable Z-scheme for charge separation. Meanwhile, the built-in electric field caused by the piezoelectric effect can act as a powerful driving force for charge separation, achieving high charge separation efficiency and promoting the utilization of photogenerated electrons. This work would provide a fresh perspective for MOF-based piezoelectric photocatalysts and have implications for the design of efficient Z-scheme heterojunctions.

Piezo-Enhanced Photocatalytic Performance of Bismuth Ferrite-Based Thin Film for Organic Pollutants Degradation

This work addresses the global sustainable development concerns by investigating the enhancement of piezo-photocatalytic efficiency in bismuth ferrite-based thin films synthesized using reactive high-power impulse magnetron sputtering. The influence of substrate type and Cr addition on structural, optical and ferroelectric properties of bismuth ferrite (BFO) based thin films was investigated. X-ray diffraction measurements showed the formation of different phases depending on the substrate used for sample growth. Compared to the BFO film deposited on FTO (F-SnO2), the Cr-doped BFO (BFCO) sample on SrTiO3 (STO) exhibits higher photodegradation efficiency (52.3% vs. 27.8%). The enhanced photocatalytic activity of BFCO is associated with a lower energy band gap (1.62 eV vs. 1.77 eV). The application of ultrasonic-wave vibrations simultaneously with visible light improved 2.85 times and 1.86 times the photocatalytic degradation efficiencies of BFO/FTO and BFCO/STO catalysts, respectively. The piezoresponse force microscopy (PFM) measurements showed that both catalysts exhibit ferroelectric behavior, but a higher piezoelectric potential was evidenced in the case of the BFO/FTO thin film. The enhancement of piezo-photodegradation efficiency was mainly attributed to the piezoelectric-driven separation and transport of photo-generated carriers toward the surface of the photocatalyst.

Bulk embedding of Ti-defected TiO2 nano-heterointerfaces in hematite photoanode for boosted photoelectrochemical water splitting

The practical application of the most promising α-Fe2O3 photoanode in solar hydrogen generation is facing an awkward challenge arising from its poor bulk carrier transport. Present work demonstrates the acceleration of the carrier transport via embedding the p-type Ti-defected TiO2 (TiO2-VTi) nanocrystals in the n-type Fe2O3 photoanode matrix, which results in significantly improved photoelectrochemical performance. By embedding sub-5 nm TiO2-VTi nanocrystals in the bulk of α-Fe2O3 photoanode, numerous p-n nano-heterointerfaces were constructed for the first time in Fe2O3 photoanode matrix. The formed p-n nano-heterointerfaces lead to 10 times enhancement of charge transfer rate constant (ktran), and 1.5 times reduction of the charge recombination rate constant (krec), which is due to the formation of the built-in electric fields and effective carrier transport and separation at the p-n nano-heterointerfaces of TiO2-VTi/Fe2O3. Such strategy leads to the Fe2O3 photoanode with a reduction of photogenerated carrier transport time by 3 times, resulting in an excellent photocurrent density as high as 1.45 mA cm−2 at 1.23 VRHE, 5 times higher than that of pristine hematite (0.27 mA cm−2). We thus believe that our study opens up a route to regulate hematite or even metal-oxide semiconductor chemical/physical features via p-n nano-heterostructure embedding.

Preparation of TiO2/SnO2 Electron Transport Layer for Performance Enhancement of All-Inorganic Perovskite Solar Cells Using Electron Beam Evaporation at Low Temperature.

SnO2 has attracted much attention due to its low-temperature synthesis (ca. 140 °C), high electron mobility, and low-cost manufacturing. However, lattice mismatch and oxygen vacancies at the SnO2/CsPbI3-xBrx interface generally lead to undesirable nonradiative recombination in optoelectronic devices. The traditional TiO2 used as the electron transport layer (ETL) for all-inorganic perovskite solar cells (PSCs) requires high-temperature sintering and crystallization, which are not suitable for the promising flexible PSCs and tandem solar cells, raising concerns about surface defects and device uniformity. To address these challenges, we present a bilayer ETL consisting of a SnO2 layer using electron beam evaporation and a TiO2 layer through the hydrothermal method, resulting in an enhanced performance of the perovskite solar cell. The bilayer device exhibits an improved power conversion efficiency of 11.48% compared to the single-layer device (8.09%). The average fill factor of the bilayer electron transport layer is approximately 15% higher compared to the single-layer electron transport layer. Through a systematic investigation of the use of ETL for CsPb3-xBrx PSCs on optical and electronic properties, we demonstrate that the SnO2/TiO2 is an efficient bilayer ETL for PSCs as it significantly enhances the charge extraction capability, suppresses carrier recombination at the ETL/perovskite interface, facilitates efficient photogenerated carrier separation and transport, and provides high current density and reduced hysteresis.

High-Efficiency InGaN Photo Cell Irradiated by 532 nm Laser with AlGaN Electron Blocking Layer

In this paper, a high-efficiency InGaN photo cell irradiated by 532 nm laser (at green wavelength) with AlGaN electron blocking layer (EBL) is proposed based on the blue-green light window effect of seawater. Firstly, the InGaN/GaN multiple quantum wells (MQWs) structured material intercalated with AlGaN EBL was designed and grown for InGaN photo cells. Then, by measuring the AFM, XRD and PL of the material, it is found that the insertion of AlGaN EBL can effectively reduce the defect density and improve the steepness of the interface in the active region. Further, based on the above material characteristics, the performance of the InGaN photo cells with AlGaN EBL is evaluated in Silvaco software under 532 nm laser irradiation. The results show that the introduction of AlGaN EBL in InGaN photo cell can not only decrease the non-radiative recombination rates, but also reduce the piezoelectric polarization effect, which contribute to the transport of effective photo-generated carriers and eventually improve the conversion efficiency by 13.325% compared to that with conventional structure. These findings provide critical new insights on high-efficiency GaN-based Photo Cell irradiated by 532 nm laser in the application of underwater communications.

Construction of a 2D lamellar membrane for a combination of photocatalytic hydrogen evolution and photothermal water evaporation

Solar energy can help solve the energy and water shortage crisis. Developing a single material that can exhibit both photocatalytic hydrogen evolution (PHE) and photothermal water evaporation (PWE) represents a new concept to simultaneously realize green energy and fresh water supply. In this study, a series of 2D lamellar membranes (2DLMs) based on a conventional semiconductor BiOCl nanosheet was designed as an ensemble, and its combined application for PHE and PWE was explored, in which cellulose nanofibers (CNFs), carbon nanotubes (CNTs), and a self-assembly of CNF@CNT were also used. The PHE and PWE efficiencies are closely related to the conversion of solar energy and the state of the water molecules. Owing to the high light-to-thermal conversion, enhanced water transfer, and the low evaporation enthalpy of confined water, a composite made of BiOCl and CNF@CNT 2DLM (BOC-CNF@CNT) could rapidly reach a surface temperature of 46.6 °C, with its PWE rate reaching up to 2.05 kg·m−2·h−1. Moreover, owing to the high photogenerated carrier transport, strong photothermal effect, and the action of confined water, the PHE rate of BOC-CNF@CNT is 1.99-fold that of the composite made of BiOCl and CNF 2DLM (BOC-CNF) and 1.42-fold that of the composite made of BiOCl and CNT 2DLM (BOC-CNT). This work provides a new and effective strategy for a comprehensive utilization of solar energy to simultaneously produce clean hydrogen and fresh water.

Boosting catalytic efficiency via BiVO4 surface heterojunction-induced interfacial Z-scheme NiFe2O4/{0 1 0}BiVO4 composite

In this work, a unique recyclable interfacial Z-scheme NiFe2O4/{010}BiVO4 composite was successfully designed by selectively loading NiFe2O4 onto the {010} facet of BiVO4 for the removal of norfloxacin (NOR) in aqueous solution. Under ultrasonic irradiation, the interfacial Z-scheme NiFe2O4/{010}BiVO4 composite exhibited a remarkable NOR removal efficiency of 98.97 % within 60 min (at an initial NOR concentration of 10 mg/L). The outstanding catalytic performance was attributed to the interfacial Z-scheme structure, which facilitates the spatial separation and transport of photo-generated carriers, and significantly prolongs their lifespan. The formation of interfacial Z-scheme NiFe2O4/{010}BiVO4 composite occurs when the {110} and {010} facets of BiVO4 are exposed to create a surface heterojunction. Moreover, the results of the recycling studies indicate the catalyst had superior stability, while its magnetic characteristics allows easy recovery. The probable degradation pathways of NOR was proposed based on the major degradation intermediates identified. This study demonstrates the idea of reducing photo-generated carrier recombination with construction of interfacial Z-scheme heterojunction, which is a promising strategy for the development of efficient catalysts.

Enhanced UV photo-detection properties of graphene oxide incorporated transparent TiO2 thin films in Schottky configuration

Here we report the modification of UV photo-response characteristics of solution processed transparent titanium dioxide-graphene oxide (TiO2-GO) nanocomposite thin films measured in metal-semiconductor (MS) Schottky junction configuration with the variation of GO content. Optical characterizations confirm the GO induced modification of optical band gap of TiO2 thin films of average thickness ∼100 nm without compromising the transparency in the visible range of electromagnetic spectrum. The nonlinear current-voltage characteristics with rectifying nature for TiO2-GO nanocomposite thin films with silver electrode indicate the formation of MS Schottky junction. The UV response characteristics like photocurrent, photo response times of the fabricated MS junctions improve significantly with the GO content in host TiO2 matrix when measured under UV light of wavelength ∼365 nm. The enhanced photocurrent (Iph) with reduced rise (tON) and recovery time (tOFF) of photo response is attributed to the GO induced modification of space charge region, passivation of interface defect states for betterment of charge carrier transport and less recombination of photo-generated charge carriers. Impedance spectra measured for nanocomposite thin films under dark and illumination confirm the modification of grain-boundary/interface to enhance the charge transport mechanism.

Construction of a 0D/3D AgI/MOF-808 photocatalyst with a one-photon excitation pathway for enhancing the degradation of tetracycline hydrochloride: Mechanism, degradation pathway and DFT calculations

One-photon excitation has been demonstrated to be ideal for improving photon utilization effectiveness. We synthesized a unique 0D/3D AgI/MOF-808 composite using a hydrothermal method combined with in situ precipitation. X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations indicated the electron migration direction, confirming the presence of a one-photon excitation pathway. The 0D/3D AgI/MOF-808 exhibited both excellent adsorption (189.01 mg/g) and photocatalytic properties for tetracycline hydrochloride (TCH). Electrochemical and photoluminescence (PL) tests showed that 0D/3D AgI (40 wt%)/MOF-808 had the highest photogenerated carrier transport and separation efficiency, with a TCH degradation efficiency of 83.02 % and a degradation rate 14.32 times higher than that of bare AgI. Photon utilization efficiency, carrier separation, and adsorption capacity expansion all contributed to the photocatalytic performance. The effects of pH and inorganic anions on the composite photocatalyst during the photocatalytic reaction were also investigated. The capture experiment demonstrated that ·OH and ·O2– were the primary active groups. Additionally, the stability was enhanced because the migration of electrons in AgI effectively limited the reduction of Ag+ to Ag0. Possible attack sites during TCH degradation were predicted using the condensed FuKui function (CFF), and potential degradation pathways were determined using ultrahigh-performance liquid chromatography–tandem mass spectrometry (UHPLC-MS/MS). The examination of the biotoxicity of TCH degradation intermediates demonstrated a reduction in their environmental risks.

Synthesis of SiO2-doped BiOX (X = Cl, Br) II-type heterojunctions and 2H-MoS2-doped SiO2@BiOX Z-scheme heterojunctions: A comparative study

In this research, II-type SiO2@BiOX (X = Cl, Br) was synthesized by loading SiO2 microspheres onto 2D layered BiOX using a simple one-step hybrid solvothermal method. On this basis, the two-dimensional bismuth oxyhalide layer was modified by using 2H-MoS2 layer and compounded with SiO2 microspheres to form 2H-MoS2@SiO2@BiOX (X = Cl, Br) Z-scheme heterostructured photocatalysts. The energy band structure and photogenerated carrier transport mechanism of the composite photocatalysts were analyzed by various characterization methods, and the transport efficiency of photogenerated carriers of II-type heterojunction and Z-scheme heterojunction were compared. The differences in photocatalytic activities of II-type heterojunctions and Z-scheme heterojunctions were shown by microscopic mechanisms and macroscopic phenomena. The photocatalytic degradation experiments showed that the doping of 2H-MoS2 acted as a conducting medium in the p-BiOX/n-SiO2 heterostructure, which changed the photogenerated electron transfer and formed the Z-scheme heterojunction structure, thus promoting the photocatalytic activity. In this study, the structure of BiOX-based composite photocatalyst was optimized and constructed, and a new idea was provided for the design and construction of II-type heterojunction and Z-scheme heterojunction photocatalysts.

Nanoarchitecture of a Two-Dimensional Few-Layer Graphene Oxide/π-Conjugated Polyimide Composite for Enhanced Photocatalytic Performance.

A novel two-dimensional graphene oxide/sulfur-doped polyimide (GO/SPI) hybrid polymer photocatalyst was synthesized by a facile ultrasonic chemical method. The characterization results showed that the skeleton structure of SPI was not changed when the few layers of GO were wrapped on the surface. Due to the excellent charge transport characteristics of GO and the strong π-π stacking interaction between two-dimensional GO and SPI, the photogenerated carrier transport capability of the GO/SPI composites was significantly enhanced compared with that of SPI. The efficient transmission and separation of photogenerated charge carriers significantly improve the photocatalytic degradation of the methyl orange activity of the GO/SPI composite. This work provides a facile and new way for the synthesis of metal-free inorganic-organic composite photocatalysts with high efficiency and low cost.

Synergetic Adsorption–Photocatalytic Activated Fenton System via Iron-Doped g-C3N4/GO Hybrid for Complex Wastewater

A synergetic adsorption–photocatalytic-activated Fenton system using an iron-doped g-C3N4/GO (GO/Fe-GCN) hybrid with highly efficient performance was established. The highly dispersed iron species with a Fe2+/Fe3+ ratio (1.67) and mesopores (3.7 nm) with a relative higher specific area and pore volume benefited the reaction efficiency and the contact of organic pollutants with the active sites. In the dynamic adsorption–photo-coordinated Fenton system, the maximum removal rate of GO/Fe-GCN reached 96.5% and equilibrium was 83.6% for Rhodamine B. The GO component not only enhanced the adsorption but also provided a higher efficiency of photo-generated carrier separation and transport. The hybrid structure of GO/Fe-GCN and the high efficiency of circulation of Fe(III)/Fe(II) played an essential role in the synergy of the adsorption–enrichment and the photo-coordinated Fenton reaction. GO/Fe-GCN can also be used to treat complex waste-water containing metallic ions, metal complexes, and organic pollutants, which could allow potential applications in the treatment of water pollution.

Investigation of in situ sulfide/nitride/phosphide treatments of hematite photoanodes for improved solar water oxidation.

Surface catalyst engineering can effectively improve the photoelectrochemical water splitting (PEC-WS) performance of semiconductor photoelectrodes. In situ surface functional treatments can effectively reduce interface defects and improve photogenerated carrier transport. In this study, FTO/Sn@α-Fe2O3/FeOOH photoanodes were modified with in situ sulfide/nitride/phosphide treatments to improve their PEC-WS performance. Compared with the pure α-Fe2O3 photoanode, the photocurrent densities of FTO/Sn@α-Fe2O3/FeOOH photoanodes after sulfide/nitride/phosphide treatments increased from 0.88 to 3.38 mA cm-2 at 1.23 VRHE. The onset potential showed a cathode shift of 0.1 V. Photoelectrochemical analyses and theoretical calculation demonstrated that the surface engineering by sulfide/nitride/phosphide treatments can significantly reduce surface defects, enhance electrical conductivity and promote photogenerated carrier separation and transfer efficiency by regulating interface charge transfer, binding energy and internal electric field. The formation of an FeSx catalyst and N/P coordination complexes in the sulfide/nitride/phosphide processes on the surface of α-Fe2O3 photoanodes can effectively reduce photogenerated carrier recombination. This work provides experimental and theoretical support for surface structure design and improved photoelectric conversion performance of semiconductor photoelectrode materials.

Constructing metal-free heterophotocatalyst using two-dimensional carbon nitride sheets and violet phosphorene for highly efficient visible-light photocatalysis

Two-dimensional (2D) carbon nitride sheets (CNs) with nanoscale thickness have great potential in solar energy conversion owing to their intrinsic bandgap. However, their photocatalytic efficiency falls far below the practical requirements because the generated electron-hole pairs rapidly recombine. We construct a metal-free 2D p–n junction heterophotocatalyst from CNs and violet phosphorene (VP) using a simple electrostatic self-assembly method. The experimental results and density functional theory calculations show that the built-in electric field of the p–n junction promotes photogenerated carrier transport at the heterojunction interface, thereby promoting the separation of photogenerated electron-hole pairs. Under visible-light illumination, the visible-light photocatalytic hydrogen and CO production rates of the CNs/VP heterojunction were increased by 5.85 and 1.51 times, respectively, when compared to that of CNs. This study provides new insights into the design of metal-free heterogeneous photocatalysts with high catalytic activity.

BiOI@CeO2@Ti3C2 MXene composite S-scheme photocatalyst with excellent bacteriostatic properties

As an influential antifouling material, photocatalytic materials have drawn attention increasingly over recent years owing to their potential bacteriostatic property in the domain of marine antifouling. Herein, a flower-like BiOI@CeO2@Ti3C2 S-scheme photocatalyst was contrived and prepared by hydrothermal method. The innovative combination of Ti3C2 and narrow band gap semiconductor BiOI was implemented to modify CeO2 and the photocatalytic bacteriostatic mechanism of BiOI@CeO2@Ti3C2 was elucidated. Schottky junction was formed between CeO2 and Ti3C2, and a p-n junction was formed between CeO2 and BiOI. By photoelectrochemical characterization, BCT-10 exhibits the best photoelectrochemical performance of which photogenerated carrier transport can be performed more readily at 10 % CeO2@Ti3C2 addition. 99.76 % and 99.89 % of photocatalytic bacteriostatic efficiency of BCT-10 against Escherichia coli and Staphylococcus aureus were implemented respectively, which were 2.98 and 3.07 times higher than that of pure CeO2. The ternary heterojunction can suppress photogenerated electron-hole complexes more effectively and enhance the photocatalytic bacteriostatic effect of CeO2, which also provided a new concept to the further broadened application of CeO2 in the marine bacteriostatic and antifouling field.

Promoting carrier collection by DMF/DMSO binary solvent for efficient kesterite solar cells

Photo-generated carrier recombination loss and transport are the key issues affecting the photovoltaic performance of kesterite solar cells. Here, through a binary solvent engineering of dimethylformamide (DMF)/dimethyl sulfoxide (DMSO) in the precursor solution, over 12% efficient Cu2ZnSn(S,Se)4 (CZTSSe) solar cells are fabricated with outstanding carrier collection. It is found that a more Cu-poor and rough film surface is formed when DMSO is partially replaced by the DMF solvent, resulting in solar cells with enhanced short-wave absorption and improved short-circuit current density. Carrier recombination and band alignment analysis show that the increased depletion width, built-in voltage, and reduced conduction band offset improve carrier separation and transport. This work provides an intrinsic origin for the performance improvement of binary solvent-engineered CZTSSe solar cells and a simple and effective method for fabricating high-performance kesterite photovoltaics.

The self-powered photodetector of n-Si/n-ZnO heterojunction with enhanced temperature adaptability via transient current response

Self-powered photodetectors (PDs) have great application potential in distributed sensor networks, imaging systems and Internet of Things (IoT) due to their simple structure and long-term mobile detection without external power supply. However, the steady-state current response of PD decreases sharply with the increase of temperature, which restricts its application in high temperature environment. Here, a self-powered PD of n-Si/n-ZnO heterojunction with transient current response has been prepared, and the current generation mechanism and response characteristics under various temperature have been studied as being excited by periodic light pulses. The results show that the transient current response can not only improve the photocurrent responsivity and specific detectivity of PD, but also improve the performance of PD at high temperature. When the temperature rises to 340 K, the transient current holding factor η t (η t′) of device excited by 127 μW cm−2, 365 nm light are increased by 115% (315%) compared with steady state current holding factor η s. The corresponding transient current enhancement factor α tt′ (α t′) of PD increase monotonically with the temperature, and the maximum values α tt′ (α t′) of PD excited by 365 nm light are 12.5 (5.0). As the temperature increases, the t r and t f of PD excited by 365 nm (287 μW cm−2) light decrease from 0.16 and 0.15 ms to 0.11 and 0.11 ms, respectively. The transient current response is caused by the transport of excess photo-generated carriers in the PD at the moment of light on and off. The transient current increases significantly with decrease resistance and is less affected by decreasing built-in electric field that make PD has high holding factor under high temperature conditions. This work provides a new avenue for designing high-performance self-powered PDs capable of operating in higher temperature environments, and promotes the wide application of transient-response self-powered PDs in the fields of IoT, fast detecting, and imaging.

Electrodeposited kochia scoparia-shaped Te film: Controlled synthesis and enhanced visible-light photocatalytic performance

Recently Te film is precisely designed to degrade organic pollutants under visible light irradiation owing to its suitable photoelectrochemical properties. Here, various nanostructured Te films are synthesized via a facile electrodeposition method. Different concentration of cetyltrimethylammonium bromide (CTAB) is added into electrolytic solution, and a novel kochia scoparia-shaped morphology with excellent photocatalytic activity is successfully synthesized. The as-fabricated kochia scoparia-shaped Te film is explored in detail via many analytical methods. The results show that as-synthesized kochia scoparia-shaped nanostructure has better crystallinity, enhanced light absorption ability, lower intensity in PL spectra, favorable photogenerated carrier transport and a significantly enhanced photodegradation ratio of methylene blue (MB), as compared to the feather-shaped Te film. The removal rates can reach up to 95.5 % on the degradation of MB in 60 min. In addition, the kochia scoparia-shaped Te film also shows good repeatability and stability without an apparent inactivation under visible light irradiation during four repeated photocatalytic processes. Furthermore, a possible reaction mechanism of higher MB degradation efficiency in the film is also proposed and discussed according to the ESR results. This work supplies a worthy reference for developing highly capable and reusable photocatalysts for eliminating various pollutants.

Facile construction of BiOBr/CoAl-LDH heterojunctions with suppressed Z-axis growth for efficient photoreduction of CO2

Due to the massive usage of fossil fuels, the carbon dioxide content in the atmosphere is increasing year by year. Meanwhile, the CO2 photoreduction has been widely researched and regarded as a promising method to utilize the CO2. BiOBr has good photocatalytic activity as a suitable photocatalyst. However, the photocatalytic performance is still unsatisfactory, and the product of CO2 photocatalytic reduction has a large proportion of CO instead of CH4. Therefore, in this paper, we prepare ultrathin CoAl-LDH by inhibiting Z-axis growth and load ultrathin CoAl-LDH on BiOBr to construct heterojunction to improve the photocatalytic efficiency of BiOBr and regulate the selectivity of the products. It was found that the loading of ultrathin CoAl-LDH helps to improve the photogenerated electron-hole pair separation ability and photogenerated carrier transport ability, thus improving the photocatalytic performance. At the same time, the loading of ultrathin CoAl-LDH helps to convert the photocatalytic CO2 reduction product from CO to CH4. After the gradient study experiment on the dosage of ultrathin CoAl-LDH, it was found that the best effect was achieved at the dosage of 10 mL of ultrathin CoAl-LDH colloidal solution, and the CO yield rate was 4.096 μmol·g−1·h−1 and CH4 yield rate was 4.174 μmol·g−1·h−1. Meanwhile, the CH4 selectivity will reach 46% of the product. In this work, we offer a novel regulation strategy for selectivity improvement of CO2 photocatalytic reduction, which can be assigned to the moderated ultrathin CoAl-LDH loading, thus enhance the selectivity of CO2 to CH4.

Efficient ultraviolet–visible-near infrared self-powered photodetector based on hexagonal YMnO3-based ferroelectric thin film by multiscale polarity structure optimization

The utilization of ferroelectric photovoltaic effect is thought to be an effective strategy to design novel self-powered photodetectors. However, the low photocurrent output due to the incompatibility between high intrinsic ferroelectric polarization and narrow bandgap is a major disadvantage that restricts photodetection performances. Here, high-efficiency photodetection properties are achieved in a hexagonal Y1-xBixMnO3 ferroelectric self-powered photodetector using a multiscale polarity structure optimization strategy. Particularly, the photodetector based on Y0.95Bi0.05MnO3 (YBMO5) can work in a wide band ranging from ultraviolet to near infrared with the maximum responsivity and detectivity up to 0.60 A/W and 2.50 × 1012 Jones, respectively, with the fast response time of only 0.3/0.4 ms, which are superior to the traditional ferroelectric perovskite photodetectors. The excellent photodetection performances originate from the enhanced photocurrent output, owing to simultaneously achieving big light absorption and robust photogenerated carrier separation and transport. It is demonstrated that Bi doping tunes crystal lattice, domain structure and the interface state, which effectively enhance macroscopic polarity in the condition of nearly unchanged bandgap. Moreover, a denser conductance network of grain boundary is constructed by decreasing grain size, which provides more transport paths for the photogenerated carriers. This work opens up a promising route for the design of high-performance ferroelectric photodetectors.