Perovskite-based Photodetectors Research Articles

CsPbBr3 perovskite quantum dots/p-GaN heterojunction for ultraviolet-visible spectrum photodetectors

All-inorganic perovskites have attracted increasing attention because of their strong environmental stability and excellent photoelectric properties. However, the limited spectral response range of perovskite photodetectors restricts them in practical applications. In this work, an ultraviolet–visible photodetector with a wide spectral response and a high responsivity was prepared by constructing a CsPbBr3 quantum dots (QDs)/p-GaN heterojunction. The type-II energy band alignment formed by the heterojunction is conducive to the transport of photogenerated carriers, resulting in a high responsivity. Under certain conditions, the device can obtain responsivity values of 5 A/W and 850 mA/W under 350 and 725 nm illumination, respectively, which are comparable to those of other perovskite-based photodetectors. In addition, the photoresponse mechanism of the device is revealed through first-principles calculations of the heterojunction and the device. The enhanced light absorption of the heterojunction and the special band bending under different bias voltages improve the photoelectric performance of the device. This work can provide valuable insights into high-performance photodetectors based on all-inorganic perovskite QDs heterojunctions in terms of band regulation and device performance improvement.

Highly stable and sensitive broadband photodetector based on BA2MAPb2I7/Si heterojunction

Quasi-2D perovskites have gained significant attention as promising two-dimensional materials for optoelectronic applications. They offer unique optical and electrical properties as well as enhanced stability compared to their 3D counterparts. In this study, we present the successful fabrication of a novel photodetector based on a BA2MAPb2I7/Si heterojunction. The optoelectronic properties of the BA2MAPb2I7/Si-based photodetector demonstrate its high sensitivity across a broad range of incident wavelengths spanning from 365 nm to 850 nm. Notably, the fabricated device exhibits an exceptional responsivity of 3.53 A/W for 850 nm radiation, surpassing the typical few mA/W responsivities achieved by a majority of previously reported perovskite-based vertical photodetectors. Furthermore, the device shows a rapid response of approximately 25.9 μs. These results highlight the potential of our fabrication approach to realize highly sensitive broadband photodetectors using a simple and cost-effective process, making them suitable for integration with Si-based electronics.

Surface Microstructure Engineering in MAPbBr3 Microsheets for Performance-Enhanced Photodetectors.

Metal halide-perovskite-based photodetectors have recently emerged as a class of promising optoelectronic devices in various fields. Meanwhile, nano/microstructuring perovskite-based photodetectors are a facile integration with complementary metal-oxide semiconductors for miniaturized imaging systems. However, there are still challenges to be overcome in reducing the losses caused by light reflection on the surface of microstructural perovskites. In this work, surface microstructure engineering is employed in MAPbBr3 microsheets for reducing light reflection and improving light absorption, resulting in high-performance perovskite photodetectors. MAPbBr3 microsheets, which possess different surface morphologies of flat, upright hemisphere arrays and inverted hemisphere arrays (IHAs), are fabricated by a simple microstructure template-assisted space confinement process. The light absorption capacity of IHA MAPbBr3 is significantly higher than that of the other two structures. Hence, IHA photodetectors with excellent figures of merit, including low dark current, decent responsivity, and fast speed, are achieved. Furthermore, the noise of the IHA photodetectors is only ∼10-13 A/, which results in the superior sensitivity for weak light detection with a specific detectivity up to 1011 Jones. Our results demonstrate that surface engineering is a simple, low-cost, yet effective approach to improve the performance of nano-/micro-optoelectronic devices.

Exploring the impact of electron transport layer thickness and morphology on perovskite infiltration and photoresponse in HTM-free self-powered photodetector

Methylammonium lead Iodide (MAPbI3) is emerging as the frontrunner for high-performance photo-detection due to its superior optoelectronic characteristics and ease of processing. Titanium dioxide (TiO2) is the commonly employed electron transport layer in conventional perovskite-based photodetectors. However, the fundamental understanding of the role of TiO2 morphology and its thickness on the photodetector performance is yet to be explored explicitly. This work systematically investigates the impact of morphology (mesoporous versus compact TiO2 layer) and thickness of the TiO2 layer (50 nm – 3000 nm) on the MAPbI3 photodetector performance. The devices have been fabricated in a hole transport material (HTM)-free architecture with carbon as the top contact. The heterojunction between MAPbI3 and TiO2 renders the device with self-powered capability. The influence of the perovskite sensitisation in the TiO2 electrodes, carrier recombination characteristics and charge-carrier transfer resistances have been studied using photoluminescence and impedance spectroscopy. The TiO2 layer morphology and thickness affected the MAPbI3 infiltration and film formation kinetics. Impedance and photoluminescence spectroscopies reveal that TiO2 layers, with thickness above 460 nm, negatively affected the device performance. An optimum thickness of 460 nm-mesoporous TiO2 layer exhibited a superior responsivity and rise time of 2.9 A/W and 21 ms, respectively. The poor performance at higher thicknesses is due to the increased interfacial charge transfer resistance and charge carrier recombination. This work is the first report of extensive optimisation and study on the impact of TiO2 film morphology and thickness on the MAPbI3 photodetectors. The present work will be a key for modelling and designing high-performance perovskite photodetectors.

Organic Electronics-Microfluidics/Lab on a Chip Integration in Analytical Applications.

Organic electronics (OE) technology has matured in displays and is advancing in solid-state lighting applications. Other promising and growing uses of this technology are in (bio)chemical sensing, imaging, in vitro cell monitoring, and other biomedical diagnostics that can benefit from low-cost, efficient small devices, including wearable designs that can be fabricated on glass or flexible plastic. OE devices such as organic LEDs, organic and hybrid perovskite-based photodetectors, and organic thin-film transistors, notably organic electrochemical transistors, are utilized in such sensing and (bio)medical applications. The integration of compact and sensitive OE devices with microfluidic channels and lab-on-a-chip (LOC) structures is very promising. This survey focuses on studies that utilize this integration for a variety of OE tools. It is not intended to encompass all studies in the area, but to present examples of the advances and the potential of such OE technology, with a focus on microfluidics/LOC integration for efficient wide-ranging sensing and biomedical applications.

Hetero-integrated MoS2/CsPbBr3 photodetector with enhanced performance via combinational modulation of grain boundary passivation and interfacial carrier separation

The distinguished electronic and optical properties of all-inorganic lead halide perovskites (CsPbX3, X = Cl, Br, I) qualify them as ideal candidates for active layer in optoelectronic devices, especially showing more competitive development prospects in photodetection with high performance. However, superior device performance and good long-term stability is still a challenge for perovskite-based photodetectors applying in practical situation. Herein, we demonstrate a novel hetero-integrated MoS2/CsPbBr3 photodetector displaying efficient device performance, where the MoS2 nanocrystals pre-synthesized by hydrothermal route were spin-coated on the surface of CsPbBr3 films with controllable dispersion, providing effective interfacial photo-carriers separation at MoS2/CsPbBr3 van der Waals heterojunction (vdWH) and significant defect passivation for perovskite grain boundaries (GBs) simultaneously, thus boosting optoelectronic performance of our device within ultraviolet (UV)-visible wavelength range, including a higher photoresponsivity (4.79 A/W), enhanced specific detectivity (8.81 × 1012 Jones) and more durable stability than that of the pristine CsPbBr3 photodetector. Furthermore, the fast response speed (0.17/0.22 ms) is obviously more outstanding than that of most CsPbBr3-based and congeneric hybrid photodetectors. These results, combined with our experimental design strategy of the device described herein, provide an efficient approach to achieve stable, high-performance photodetection using perovskite-based hybrid nanomaterial systems, thus opening up new possibilities for two-dimensional (2D) materials/perovskites hetero-integration based photovoltaic and optoelectronic applications in the future.

Ultraviolet-Visible-Short-Wavelength Infrared Broadband and Fast-Response Photodetectors Enabled by Individual Monocrystalline Perovskite Nanoplate.

Perovskite-based photodetectors exhibit potential applications in communication, neuromorphic chips, and biomedical imaging due to their outstanding photoelectric properties and facile manufacturability. However, few of perovskite-based photodetectors focus on ultraviolet-visible-short-wavelength infrared (UV-Vis-SWIR) broadband photodetection because of the relatively large bandgap. Moreover, such broadband photodetectors with individual nanocrystal channel featuring monolithic integration with functional electronic/optical components have hardly been explored. Herein, an individual monocrystalline MAPbBr3 nanoplate-based photodetector is demonstrated that simultaneously achieves efficient UV-Vis-SWIR detection and fast-response. Nanoplate photodetectors (NPDs) are prepared by assembling single nanoplate on adjacent gold electrodes. NPDs exhibit high external quantum efficiency (EQE) and detectivity of 1200% and 5.37 × 1012 Jones, as well as fast response with rise time of 80 µs. Notably, NPDs simultaneously achieve high EQE and fast response, exceeding most perovskite devices with multi-nanocrystal channel. Benefiting from the high specific surface area of nanoplate with surface-trap-assisted absorption, NPDs achieve high performance in the near-infrared and SWIR spectral region of 850-1450nm. Unencapsulated devices show outstanding UV-laser-irradiation endurance and decent periodicity and repeatability after 29-day-storage in atmospheric environment. Finally, imaging applications are demonstrated. This work verifies the potential of perovskite-based broadband photodetection, and stimulates the monolithic integration of various perovskite-based devices.

Large-Scale, Uniform-Patterned CsCu2 I3 Films for Flexible Solar-Blind Photodetectors Array with Ultraweak Light Sensing.

Cesium copper halide perovskite is one of the promising materials for solar-blind light detection. However, most of the cesium copper halide perovskite-based photodetectors (PDs) are focused on ultraviolet A detection and realized on the rigid substrate in the single device configuration. Here, a flexible solar-blind PDs array (10×10 pixels) based on the CsCu2 I3 film patterns for ultraweak light sensing and light distribution imaging is reported. Large-scale CsCu2 I3 film arrays are synthesized with various shapes and uniform dimensions through a simple vacuum-heating-assisted solution method. Benefiting from excellent air stability and superior resistance to the photodegrading of the CsCu2 I3 film, the array device exhibits long-term stable photoswitching behavior for 8h and ultralow light detection capability to resolve the light intensity of 6.1 nW cm-2 with a high responsivity of 62 A W-1 , and the array device can acquire clear images of "G", "X", and "U" showing the input light distribution. Moreover, the flame detection and warning system based on a curved solar-blind PDs array is demonstrated, which can be used for multi-flame monitoring and locating. These results can encourage potential applications of the CsCu2 I3 film-based PDs array in the field of optical communication and environment monitoring.

Superior performance and ultrafast response from CH3NH3PbI3 based UV–visible broadband photodetector using 1D carrier transport layers

We have designed and fabricated two perovskite-based photodetectors (PPDs) with 2D and 1D metal oxide carrier transport layers having the structure of ZnO thinfilm (TF)/CH3NH3PbI3/NiO TF (Device1) and ZnO nanowire (NW)/CH3NH3PbI3/NiO NW (Device2). Vertical and porous 1D carrier transport layers were fabricated using the advanced glancing angle deposition (GLAD) technique. The structure with 1D carrier transport layers in Device2 showed an enhanced optical absorption and emission as compared to 2D layered structure in Device1. The Device2 would enhance the responsivity (Rλ) upto 134 times in UV (390 nm) and 1350 times in visible (450 nm) region as compared to Device1. Moreover, the maximum detectivity (D*) values of 3.43 × 1011 Jones and 3.53 × 1011 Jones were observed for Device2 and 0.343 × 1011 and 0.35 × 1010 Jones for Device1 in UV and visible regions respectively. In addition to that, the Device2 also showed an external quantum efficiency (EQE) of 3.2 × 103% and 2.9 × 103% in UV and visible regions respectively. Furthermore, the Device2 showed an ultrafast device response with rise time and fall times of 0.17 s and 0.13 s respectively. The 1D carrier transport layers in PPDs can be used as good candidate for future broadband photodetectors (PDs).

De Novo Studies of Working Mechanisms for Self-Driven Narrowband Perovskite Photodetectors.

Self-driven narrowband perovskite photodetectors have recently attracted significant attention due to their simple preparation, high performance, and amenability for system integration. However, the origin of narrowband photoresponse and the related regulation mechanisms still remains elusive. To address these issues, we herein perform a systematic investigation by formulating an analytic model in conjunction with finite element simulation. The optical and electrical simulations have resulted in design principles for perovskite narrowband photodetectors in terms of the dependence of external quantum efficiency (EQE) on perovskite layer thickness, doping concentration, and band gap as well as trap state concentration. Careful investigations on the profiles of electric field, current, and optical absorption reveal the dependence of narrowband EQE on the direction of incident light and perovskite doping types: only p-type perovskite can yield the narrowband photoresponse for illumination from the hole transport layer (HTL) side. The simulation results demonstrated in this study shed new light on the mechanism of perovskite-based narrowband photodetectors and provide valuable guidance for their design.

Highly efficient and stable near-infrared photodetectors enabled from passivated tin–lead hybrid perovskites

Tin–lead perovskite-based photodetectors have a wide light-absorption wavelength range, which spans 1000 nm. However, the preparation of the mixed tin–lead perovskite films faces two great obstacles, namely easy oxidation of Sn2+ to Sn4+ and fast crystallization from tin–lead perovskite precursor solutions, thus further resulting in poor morphology and high density of defects in tin–lead perovskite films. In this study, we demonstrated a high-performance of near-infrared photodetectors prepared from a stable low-bandgap (MAPbI3)0.5(FASnI3)0.5 film modified with 2-fluorophenethylammonium iodide (2-F-PEAI). The addition engineering can efficiently improve the crystallization of (MAPbI3)0.5(FASnI3)0.5 films through the coordination binding between Pb2+ and N atom in 2-F-PEAI, and resulting in a uniform and dense (MAPbI3)0.5(FASnI3)0.5 film. Moreover, 2-F-PEAI suppressed Sn2+ oxidation and effectively passivated defects in the (MAPbI3)0.5(FASnI3)0.5 film, thereby significantly reducing the dark current in the PDs. Consequently, the near-infrared photodetectors showed a high responsivity with a specific detectivity of over 1012 Jones at 800 to near-1000 nm. Additionally, the stability of PDs incorporated with 2-F-PEAI has been significantly improved under air conditions, and the device with the 2-F-PEAI ratio of 400:1 retained 80% of its initial efficiency after 450 h storage in air without encapsulation. Finally, 5 × 5 cm2 photodetector arrays were fabricated to demonstrate the potential utility of the Sn–Pb perovskite photodetector in optical imaging and optoelectronic applications.

High-performance layer-structured Si/Ga2O3/CH3NH3PbI3 heterojunction photodetector based on a Ga2O3 buffer interlayer.

Organic-inorganic metal halide perovskite-based photodetectors (PDs) have attracted great attention because they exhibit extraordinary optoelectronic performances due to advantages such as a low trap-state density and large absorption coefficient. As a buffer layer, G a 2 O 3 can block electron hole recombination, passivate an Si surface, reduce trap density, and improve the ability of electron tunneling. Here, we demonstrate a trilayer hybrid structure (S i/G a 2 O 3/C H 3 N H 3 P b I 3) composed of an n-type silicon wafer, G a 2 O 3 interlayer, and C H 3 N H 3 P b I 3 thin film. The effect of different G a 2 O 3 layer thicknesses on the characteristics of a PD was studied, which shows that the responsivity first increases and then decreases with an increase in the G a 2 O 3 film thickness; the optimized G a 2 O 3 thickness is 300nm. Additionally, the optimal responsivity, detectivity, and the rise and decay times are 7.2m A W -1, 7.448×1010 Jones, and 39 and 1.7ms, respectively. This device has a better performance because G a 2 O 3 and perovskite have a matched energy level. We believe our work could provide a new way to fabricate high-performance optoelectronic devices.

Multifunctional l-tryptophan derivative induced surface passivation for lateral perovskite photodetectors

Organic-inorganic hybrid perovskites have already been employed as promising light-sensitive materials for high-performance photodetectors (PDs) due to their intriguing optoelectronic features. Nonetheless, such perovskite-based PDs often suffer from low sensitivity, high dark current and inevitable degradation. In this work, a novel multifunctional molecule l-tryptophan ethyl ester hydrochloride (l-TEEH) was used to treat the surface defects of triple-cation mixed halide perovskite film. It is found that the modulator with multiple functional groups can effectively passivate the uncoordinated ions (Pb2+ and I-) and halide (I and Cl) vacancies of the perovskite film. Owing to the reduced defects, the dark current of the pristine perovskite PD significantly decreases from ∼ 10-9 A to ∼ 10-11 A after the l-TEEH treatment. Moreover, the perovskite PD with the l-TEEH treatment exhibits a large photoresponsivity (1.27 A/W) and an ultrahigh on/off ratio (∼9 × 103). More impressively, the optimized device shows excellent stability in air with a relative humidity of 40–50 %. Furthermore, the reliable imaging capability of perovskite device with the l-TEEH treatment is also successfully demonstrated.

Anisotropic Growth of Centimeter-Size CsCu2 I3 Single Crystals with Ultra-Low Trap Density for Aspect-Ratio-Dependent Photodetectors.

Low-dimensional ternary copper iodide metal halide with strong quantum confinement effects has made great progress in optoelectronic fields. However, efficient regulation of anisotropic growth of metal halides single crystal still remains a great challenge. Herein, 2cmsize CsCu2 I3 single crystals with tunable aspect ratio and the trap states (ntrap ) as low as 5.38×109 cm-3 are fabricated by optimized anti-solvent vapor-assisted method, in which the growth cycle is shortened by half. Evidenced by real-time observation and the LaMer growth model, the rapid and anisotropic growth mechanism is ascribed to preferential 1D growth, promoted by high concentration and fast vapor rate. Furthermore, the aspect-ratio-dependent optoelectronic performance is observed, the on-off ratio for 2cm CsCu2 I3 single crystal are enhanced 350 times compared with those of short and thick single crystal, which shows ultrahigh on-off ratio of 1570, D* of 1.34×1012 Jones, Rλ of 276.94mAW-1 , t rise /t decay of 0.37 and 1.08ms, and EQE of 95.53%, which are clearly at very high level among lead-free perovskite-based photodetectors. This study not only provides a new strategy for overcoming anisotropic growth limitations of low-dimensional metal halides, but also paves a way for high-performance optoelectronic applications.

Phase‐Modulated Multidimensional Perovskites for High‐Sensitivity Self‐Powered UV Photodetectors

2D Ruddlesden-Popper perovskites (PVKs) have recently shown overwhelming potential in various optoelectronic devices on account of enhanced stability to their 3D counterparts. So far, regulating the phase distribution and orientation of 2D perovskite thin films remains challenging to achieve efficient charge transport. This work elucidates the balance struck between sufficient gradient sedimentation of perovskite colloids and less formation of small-n phases, which results in the layered alignment of phase compositions and thus in enhanced photoresponse. The solvent engineering strategy, together with the introduction of poly(3,4-ethylene-dioxythiophene):polystyrene sulfonate (PEDOT:PSS) and PC71 BM layer jointly contribute to outstanding self-powered performance of indium tin oxide/PEDOT:PSS/PVK/PC71 BM/Ag device, with a photocurrent of 18.4µA and an on/off ratio up to 2800. The as-fabricated photodetector exhibits high sensitivity characteristics with the peak responsivity of 0.22AW-1 and the detectivity up to 1.3×1012 Jones detected at UV-A region, outperforming most reported perovskite-based UV photodetectors and maintaining high stability over a wide spectrum ranging from UV to visible region. This discovery supplies deep insights into the control of ordered phases and crystallinity in quasi-2D perovskite films for high-performance optoelectronic devices.

Recent progress in construction methods and applications of perovskite photodetector arrays.

Metal halide perovskites are considered promising materials for next-generation optoelectronic devices due to their excellent optoelectronic performances and simple solution preparation process. Precise micro/nano-scale patterning techniques enable perovskite materials to be used for array integration of photodetectors. In this review, the device types of perovskite-based photodetectors are introduced and the structural characteristics and corresponding device performances are analyzed. Then, the typical construction methods suitable for the fabrication of perovskite photodetector arrays are highlighted, including surface treatment technology, template-assisted construction, inkjet printing technology, and modified photolithography. Furthermore, the current development trends and their applications in image sensing of perovskite photodetector arrays are summarized. Finally, major challenges are presented to guide the development of perovskite photodetector arrays.

A Review of Perovskite-Based Photodetectors and Their Applications.

Perovskite photodetectors have attracted much research and attention because of their outstanding photoelectric characteristics, such as good light harvesting capability, excellent carrier migration behavior, tunable band gap, and so on. Recently, the reported studies mainly focus on materials synthesis, device structure design, interface engineering and physical mechanism analysis to improve the device characteristics, including stability, sensitivity, response speed, device noise, etc. This paper systematically summarizes the application fields and device structures of several perovskite photodetectors, including perovskite photoconductors, perovskite photodiodes, and perovskite phototransistors. Moreover, based on their molecular structure, 3D, 2D, 1D, and 0D perovskite photodetectors are introduced in detail. The research achievements and applications of perovskite photodetectors are summarized. Eventually, the future research directions and main challenges of perovskite photodetectors are prospected, and some possible solutions are proposed. The aim of the work is to provide a new thinking direction for further improving the performance of perovskite photodetectors.

Hybrid perovskite X-ray detectors with enhanced radioluminescence via thermally activated delayed fluorescence

Recently, metal halide perovskites have received great attention for detecting ionizing radiation. Perovskite-based photodetectors and scintillators have been successfully implemented for X-ray and γ-ray detection due to their high attenuation coefficient and excellent optoelectronic properties. However, relatively thick absorbing layers are required for the complete absorption of X-ray photons, which are very challenging to fabricate with solution processes. In this work, we designed hybrid devices coupled with excellent perovskite photodiodes to utilize the incident X-rays fully. Considering the heavy reabsorption of the perovskite layers, we blended CsPbBr3 with a Cu(I)-containing thermally activated delayed fluorescent complex (MAC*)Cu(Cz) to achieve down-conversion luminescence effectively to maximize the radioluminescence quantum efficiency, and we also found a faster afterglow compared with the commercial scintillators. Furthermore, we systematically investigated the performance metrics of the CsPbIBr2 photodiodes and scintillator films. The hybrid devices demonstrated significantly improved X-rays sensitivity, indicating potential for X-ray detection and imaging.

A Study to Improve the Performance of Mixed Cation-Halide Perovskite-Based UVC Photodetectors.

Photodetectors convert optical signals into electrical signals and demonstrate application potential in various fields, such as optical communication, image detection, environmental monitoring, and optoelectronics. In this study, a mixed cation–halide perovskite-based ultraviolet C photodetector was fabricated using a solution process. The higher the mobility of the perovskite carrier, which is one of the factors affecting the performance of electronic power devices, the better the carrier diffusion. The on/off ratio and responsivity indicate the sensitivity of the response, and together with the detectivity and external quantum efficiency, these parameters demonstrate the performance of the detector. The detector fabricated in this study exhibited a mobility of 202.2 cm2/Vs and a high on/off ratio of 105% at a −2 V bias, under 254 nm light irradiation with an intensity of 0.6 mW/cm2. The responsivity, detectivity, and external quantum efficiency of the as-fabricated detector were 5.07 mA/W, 5.49 × 1011 Jones, and 24.8%, respectively. These findings demonstrate that the solution process employed in this study is suitable for the fabrication of mixed cation–halide perovskites which show immense potential for use as photodetectors.

Perovskite-Type 2D Materials for High-Performance Photodetectors.

Photodetectors are light sensors in widespread use in image sensing, optical communication, and consumer electronics. In current smart optoelectronic technology, conventional semiconductors have encountered a bottleneck caused by inflexibility and opacity. With the ever-increasing demands for versatile optoelectronic applications, perovskite-type 2D materials demonstrate great potential for advanced photodetectors inspired by molecularly thin 2D materials. Through the reduction of thickness to thin or molecularly thin levels, single-crystalline 2D perovskites can exhibit superior optoelectronic performance characteristics, such as tunable absorption property by chemical design, enhanced carrier separation by remarkable photosensing capability, and improved carrier extraction by versatile band engineering. More importantly, perovskite-type 2D materials exhibit great potential for large-scale monolithic integration to achieve all-in-one sensing-memory-computing optoelectronic devices. In this Perspective, recent progress in 2D perovskite-based photodetectors is presented in detail. The focus is on growth strategies for reducing thickness, thickness-dependent optical and electrical properties, device engineering, heterojunction fabrication, and device performance. Finally, the current challenges and future prospects in this field are presented.