Photodetectors Research Articles

Indeno[3,2-b]carbazole-Based Small Molecule Layer Enables Optimized Carrier Transport for PbS Quantum Dot NIR Photodetectors.

Colloidal quantum dots (CQDs) have garnered considerable attention for photodetectors (PDs), attributable to exceptional photoelectric properties and ease solution-based processing. However, the prevalent use of 1,2-ethanedithiol (EDT) as a hole transport layer (HTL) has limitations, such as energy level discrepancies, requisite oxidation, and intricate multilayer assembly. Organic p-type materials, lauded for their superior attributes and synthetic versatility, are now stepping forward as viable substitutes for conventional EDT HTLs. In this work, we introduced an organic HTL derived from indolo[3,2-b]carbazole, named ZL004, leading to a marked improvement in carrier generation and collection, facilitated by the optimized band alignment and enhanced interfacial charge dynamics. The ZL004-based PDs exhibit a photoresponsivity of 0.45 A/W, a noise current of 1.8 × 10-11 A Hz-0.5, a specific detectivity of 4.6 × 109 Jones, and an expansive linear dynamic range of 107 dB─surpassing EDT-based devices across the board, demonstrating the extraordinary property of organic p-type materials for CQD-based PDs.

Dark Current in Broadband Perovskite-Organic Heterojunction Photodetectors Controlled by Interfacial Energy Band Offset.

Lead halide perovskite and organic semiconductors are promising classes of materials for photodetector (PD) applications. State-of-the-art perovskite PDs have performance metrics exceeding silicon PDs in the visible. While organic semiconductors offer bandgap tunability due to their chemical design with detection extended into the near-infrared (NIR), perovskites are limited to the visible band and the first fraction of the NIR spectrum. In this work, perovskite-organic heterojunction (POH) PDs with absorption up to 950nm are designed by the dual contribution of perovskite and the donor:acceptor bulk-heterojunction (BHJ), without any intermediate layer. The effect of the energetics of the donor materials is systematically studied on the dark current (Jd) of the device by using the PBDB-T polymer family. Combining the experimental results with drift-diffusion simulations, it is shown that Jd in POH devices is limited by thermal generation via deep trap states in the BHJ. Thus, the best performance is obtained for the PM7-based POH, which delivers an ultra-low noise current of 2×10-14AHz-1/2 and high specific detectivity of 4.7×1012Jones in the NIR. Last, the application of the PM7-based POH devices as NIR pulse oximeter with high-accuracy heartbeat monitoring at long-distance of 2 meters is demonstrated.

Silicon Nanoribbon Arrays Based Printed Multifunctional Flexible Photovoltaic Microcells

AbstractThe photovoltaic devices offer promising eco‐friendly solution for self‐powered flexible electronics. However, their fabrication on flexible substrate is not easy due to mismatches between the requirements of conventional microfabrication and the thermal, and mechanical features of the substrates. Herein, direct roll printed nanoscale photoactive electronic layers are presented, which are further processed to develop ≈315 µm2 sized miniaturized photovoltaic microcells. Using a set of 32 microcells, connected in parallel configuration, indoor light harvesting is shown at a maximum power density of ≈10 µW cm−2 under white LED illumination. Further, the dual functionality of developed microcells i.e., energy harvesting as well as wideband photodetection is demonstrated. As self‐powered photo sensors the developed photovoltaic microcells exhibit distinctive photo responses under white LED‐UV (365 nm)‐ NIR (850 nm) light illumination, with exceptionally high‐speed response (rise time τRise = 205 µs and fall time τFall = 2000 µs), and a peak responsivity of 2.48 A W−1 to UV light at zero bias voltage. The presented results show the potential usage of printed multifunctional photovoltaic microcells in a wide variety of applications such as self‐powered wearable and flexible electronic systems for health monitoring and indoor robotics.

The Rise of 2D Materials‐Based Photoelectrochemical Photodetectors: Progress and Prospect

Abstract2D materials have garnered significant research attention due to their unique electrical and optical properties. Various photodetectors (PDs) based on 2D materials have been demonstrated to possess a high photoresponse, achieve specific light detection, and construct flexible devices. Among these, photoelectrochemical‐type (PEC) PDs are attracting increasing attention due to their facile fabrication processes, self‐powered capability, and high sensitivity. Compared with transitional solid‐state PDs based on 2D materials, research on 2D material‐based PEC PDs is still in its initial stages but exhibits promising potential for various applications. This paper comprehensively reviews recent advancements in 2D material‐based PEC PDs. The 2D materials for PEC PDs are first classified, and then the synthesis methods employed for their fabrication are briefly summarized. Later, the performance and performance optimization strategies of various 2D material‐based PEC PDs are discussed. Finally, the challenges and opportunities for developing high‐performance 2D material‐based PEC PDs are highlighted.

Selective area grown photonic integrated chips for completely suppressing the Stokes shift

In this work, we report on the selective area growth (SAG) of InGaN multiple quantum well (MQW) structures to completely suppress the phenomenon of the Stokes shift in monolithically integrated photonic chips. The original green MQW region is designed as the integrated photodetector (PD), while the SAG blue MQW region acts as the integrated light-emitting diode (LED). The detection spectra of the PD can completely cover the emission spectra of the LED, greatly improving the on-chip optical connection by the complete suppression of the Stokes shift. Thus, the bottleneck of on-chip optical connection based on spectra-tail overlap in integrated photonic chips has been broken. Under the same operating current, the photocurrent of the SAG integrated PD reaches 11.8 μA, while the conventional chip achieves only 0.6 μA. By SAG method, the photo-to-dark current ratio of integrated PD exhibits about two orders of magnitude increase under 0 V bias. Undoubtedly, the SAG technology provides a strategy to further improve the on-chip optical signal transmission efficiency of the MQW structure integrated photonic chips.

NLOS visible light positioning and communication based on LoRa modulation.

With the rapid development of the Internet of Things, location-based services are becoming increasingly important, especially in indoor environments. Visible light positioning (VLP) has garnered widespread attention due to its high accuracy, low cost, and immunity to the radio frequency electromagnetic interference. However, traditional VLP relies on line-of-sight paths, making it impractical in complex and dynamic indoor environments. In this paper, we propose a non-line-of-sight (NLOS) visible light positioning and communication system based on LoRa modulation to address the issue of link obstruction. LoRa is employed to recover position information transmitted from light emitting diodes (LEDs) over NLOS links, enabling reliable communication under weak lighting conditions. We establish a geometric relationship between the LED and the virtual image of the photodetector (PD). Leveraging the NLOS channel model, we derive the relationship between the received signal strength and the distance from LEDs to the virtual image of the PD. Through this relationship, the trilateration method is applied to calculate the position of the receiver. Based on experimental results, the proposed system achieves 90th percentile localization accuracy of less than 25 and 35 cm for the PD heights of 60 and 80 cm, respectively.

Image-based corn seed embryo orientation detection and adjustment for precision planting

Research has indicated that positioning a corn seed with its embryo side facing upward and its long axis perpendicular to a seeding row leads to the corn leaves growing perpendicular to the seeding row. This positioning results in an increased rate of light interception and yield for the crop. An identification and adjustment prototype was designed to rearrange corn seeds into the aforementioned seed orientation. The main parts are the teeth plate, V-shaped groove, photo sensor, camera, LED light, and pneumatic solenoid valve. When a corn seed enters the prototype, it will first be led to a leaning state, then go through an image acquisition and processing process, where the template matching method will be used to find a region of interest (ROI) on a corn seed image. The embryo side will be identified based on the average normalized saturation value in the ROI. The pneumatic solenoid valve will then be activated to adjust the seed accordingly to the targeted seed orientation. Trial results showed a success rate of 84 % and an average adjustment time of 1.438 s. The proposed method of embryo side direction identification and adjustment will contribute to the development of corn-oriented seeding technology.

Low-cost and efficient all group-IV visible/shortwave infrared dual-band photodetector.

Low-cost broadband photodetectors (PDs) based on group-IV materials are highly demanded. Herein, a vertical all group-IV graphene-i-n (Gr-i-n) structure based on sputtering-grown undoped Ge0.92Sn0.08/Ge multiple quantum wells (MQWs) on n-Ge substrate was proposed to realize efficient visible/shortwave infrared (VIS/SWIR) dual-band photoresponse. Harnessing Gr-germanium tin (GeSn)/Ge MQWs van der Waals heterojunctions, an extended surface depletion region was established, facilitating separation and transportation of photogenerated carriers at VIS wavelengths. Consequently, remarkable VIS/SWIR dual-band response ranging from 400 to 2000 nm with a rapid response time of 23 μs was achieved. Compared to the PD without Gr, the external quantum efficiency at 420, 660, and 1520 nm was effectively enhanced by 10.2-, 5.2-, and 1.2-fold, reaching 40, 42, and 50%, respectively. This research paves the way for the advancement of all group-IV VIS/SWIR broadband PDs and presents what we believe to be a novel approach to the design of low-cost broadband PDs.

Preferred Orientation and Phase Distribution of Quasi-2D Perovskite for Bifunctional Light-Emitting Photodetectors.

In traditional optical wireless communication (OWC) systems, the simultaneous use of multiple sets of light-emitting diodes (LEDs) and photodetectors (PDs) increases the system complexity and instability. Here we report bifunctional light-emitting photodetectors (LEPDs) fabricated with quasi-2D perovskite (F-PEA)2Cs4Pb5I11Br5 as light-emitting/detecting layers for efficient, miniaturized, and intelligent bidirectional OWC. By simply changing the solvent composition of the precursor solution and using antisolvent engineering, we manipulated the crystal orientation and phase distribution of (F-PEA)2Cs4Pb5I11Br5, realizing high irradiance (4.36 μW cm-2) and a -3 dB refresh rate (0.21 MHz) of electroluminescence in LED mode as well as low noise (below 1 pA Hz-1/2) and high responsivity (0.1 A W-1) in PD mode. The rapid and accurate OWC process was demonstrated through interaction of LEPDs. We also demonstrated the high-fidelity compression and digitization of high-resolution (256 × 256 pixels) color images using the four-step phase shift method to realize intelligent encrypted image OWC.

Unbiased method for spectral analysis of cells with great diversity of autofluorescence spectra.

Autofluorescence is an intrinsic feature of cells, caused by the natural emission of light by photo-excitatory molecular content, which can complicate analysis of flow cytometry data. Different cell types have different autofluorescence spectra and, even within one cell type, heterogeneity of autofluorescence spectra can be present, for example, as a consequence of activation status or metabolic changes. By using full spectrum flow cytometry, the emission spectrum of a fluorochrome is captured by a set of photo detectors across a range of wavelengths, creating an unique signature for that fluorochrome. This signature is then used to identify, or unmix, that fluorochrome's unique spectrum from a multicolor sample containing different fluorescent molecules. Importantly, this means that this technology can also be used to identify intrinsic autofluorescence signal of an unstained sample, which can be used for unmixing purposes and to separate the autofluorescence signal from the fluorophore signals. However, this only works if the sample has a singular, relatively homogeneous and bright autofluorescence spectrum. To analyze samples with heterogeneous autofluorescence spectral profiles, we setup an unbiased workflow to more quickly identify differing autofluorescence spectra present in a sample to include as "autofluorescence signatures" during the unmixing of the full stained samples. First, clusters of cells with similar autofluorescence spectra are identified by unbiased dimensional reduction and clustering of unstained cells. Then, unique autofluorescence clusters are determined and are used to improve the unmixing accuracy of the full stained sample. Independent of the intensity of the autofluorescence and immunophenotyping of cell subsets, this unbiased method allows for the identification of most of the distinct autofluorescence spectra present in a sample, leading to less confounding autofluorescence spillover and spread into extrinsic phenotyping markers. Furthermore, this method is equally useful for spectral analysis of different biological samples, including tissue cell suspensions, peripheral blood mononuclear cells, and in vitro cultures of (primary) cells.

Li-Fi Technology for Vehicle-To-Vehicle

The integration of Light Fidelity (Li-Fi) technology within Smart Cities to enhance vehicle-to-vehicle (V2V) communication systems. Highlighting the limitations of traditional radio frequency (RF) methods in managing increasing traffic and potential ecosystem impacts, the abstract introduces Li-Fi as a promising alternative. Li-Fi utilizes visible light to achieve high-speed data transfer rates, offering advantages such as enhanced efficiency, reduced latency, improved reliability, and heightened security. The objectives of implementing Li-Fi in V2V communication are delineated, emphasizing its potential to facilitate real-time data exchange crucial for autonomous driving and safety applications. The abstract further details the methodology and architecture of Li-Fi technology, illustrating its utilization of LED bulbs and photo detectors for data transmission and reception. Practical implementation strategies for integrating Li-Fi into V2V communication systems, including sensor-based distance measurement and automated collision avoidance mechanisms, are discussed. Ultimately, the abstract concludes by emphasizing Li-Fi's potential as a cost-effective solution to mitigate traffic accidents and enhance communication efficiency in Smart Cities. Keywords — Li-Fi, Illumination, Wi-Fi, LED, Photo Diode, Radio Frequency

Low-Intensity Light Detection with a High Detectivity Using 2D-Sb2Se3 Nanoflakes on 1D-ZnO Nanorods as Heterojunction Photodetectors.

Multifunctional photodetectors (PDs) with broadband responsivity (R) and specific detectivity (D*) at low light intensities are gaining significant attention. Thus, we report a bilayer PD creatively fabricated by layering two-dimensional (2D) Sb2Se3 nanoflakes (NFs) on one-dimensional (1D) ZnO nanorods (NRs) using simple thermal transfer and hydrothermal processes. The unique coupling of these two layers of materials in a nanostructured form, such as 2D-Sb2Se3 NFs/1D-ZnO NRs, provides an effective large surface area, robust charge transport paths, and light-trapping effects that enhance light harvesting. Furthermore, the combination of both layers can effectively facilitate photoactivity owing to proper band alignment. The as-fabricated device demonstrated superior overall performance in terms of a suitable bandwidth, good R, and high D* under low-intensity light, unlike the single-layered 1D-ZnO NRs and 2D-Sb2Se3 NF structures alone, which had poor detectivity or response in the measured spectral range. The PD demonstrated a spectral photoresponse ranging from ultraviolet (UV) to visible (220-628 nm) light at intensities as low as 0.15 mW·cm-2. The PD yielded a D* value of 3.15 × 1013 Jones (220 nm), which reached up to 5.95 × 1013 Jones in the visible light region (628 nm) at a 3 V bias. This study demonstrated that the 2D-Sb2Se3 NFs/1D-ZnO NRs PD has excellent potential for low-intensity light detection with a broad bandwidth, which is useful for signal communications and optoelectronic systems.

Monolayer graphene/GaN heterostructure photodetector with UV-IR dual-wavelength photoresponses

An ultraviolet-infrared (UV-IR) dual-wavelength photodetector (PD) based on a monolayer (ML) graphene/GaN heterostructure has been successfully fabricated in this work. The ML graphene was synthesized by chemical vapor deposition (CVD) and subsequently transferred onto GaN substrate using polymethylmethacrylate (PMMA). The morphological and optical properties of the as-prepared graphene and GaN were presented. The fabricated PD based on the graphene/GaN heterostructure exhibited excellent rectify behavior by measuring the current–voltage (I–V) characteristics under dark conditions, and the spectral response demonstrated that the device revealed an UV-IR dual-wavelength photoresponse. In addition, the energy band structure and absorption properties of the ML graphene/GaN heterostructure were theoretically investigated based on density functional theory (DFT) to explore the underlying physical mechanism of the two-dimensional (2D)/three-dimensional (3D) hybrid heterostructure PD device. This work paves the way for the development of innovative GaN-based dual-wavelength optoelectronic devices, offering a potential strategy for future applications in the field of advanced photodetection technology.Graphical

Frequency-octupled millimeter-wave ROF system without bit walk-off effect by polarization modulators

A novel, to the best of our knowledge, frequency-octupled millimeter-wave (MMW) radio over fiber (ROF) system without bit walk-off effect, based on two polarization modulators (PoIM) connected in parallel, is proposed. At the central station, the downlink data signal is split into two beams; one beam modulates the radio frequency (RF) carrier through an electrical phase modulator (PM), the other beam is amplified by an electrical amplifier (EA), and the two beams are combined into one, which is used as the RF driving signal of the PoIM. By adjusting the modulation index of the PoIMs, the phase shift of the phase shifter, and the polarization angle of the polarizer (Pol), the main components of the output signal from the PoIMs are ±4th-order sidebands. By adjusting the phase modulation index of the PM and the amplification of the EA, the downlink data signal is modulated only on the +4th-order sideband. At the base station, a part of the −4th-order sidebands are reflected by a fiber Bragg grating (FBG) and used as the optical carrier for uplink for carrier reuse; the ±4th-order sidebands passing the FBG are injected into the photodetector (PD) for photoelectrical conversion, and the frequency-octupled MMW with the downlink data signal is generated. The main innovation of the scheme proposed in this paper is that the data of the uplink and the downlink is modulated on ±4th-order sidebands separately, which eliminates the periodic fading effect and bit walk-off effect due to fiber dispersion and greatly improves the fiber transmission distance of the system, and also avoids the problems of DC bias drift and extinction ratio limitation of the Mach–Zehnder modulator.

Gradient Dion‐Jacobson Phase Stable Quasi‐2D Perovskite@Graphene Hybrid for High Responsivity Photodetectors

AbstractQuasi‐(2D) formamidinium lead‐iodide (FAPbI3) perovskites are winsome materials for high‐performance photodetectors (PDs). Between Ruddlesden‐Popper (RP) and Dion‐Jacobson (DJ) phases, the latter exhibits lower non‐radiative recombination and higher mobility compared to the relatively easily synthesized former. For efficient charge separation and transport, graphene‐assisted two‐terminal coplanar PD leveraging the DJ phase perovskite is proposed. Diamino octane (DAO), incorporated into 3D FAPbI3 perovskite, resulted in DJ phase [DAO(FA)n‐1PbnI3n+1], n being predefined integers 1≤ n ≤ ∞, demonstrating a vertical gradient heterostructure of n phases. Superior crystallinity and thermal stability of the quasi‐2D films are confirmed via synchrotron‐based studies. Band‐edge of the 3D film blue‐shifted consistently from 810 nm, while passing through the quasi‐2D phases, to ≈500 nm for the 2D phase. The dynamic range of photoresponsivity (R) of PDs reflected the absorption trend, with the 2D perovskite being infrared blind. Graphene's high carrier mobility coupled with the perovskite's high absorbance resulted in an unprecedented high R of ≈107 A W−1 and specific detectivity of 9.77 × 1016 Jones under 42.25 nW cm−2 of 405 nm illumination for the predefined n = 2 film. This underscores the potential of the DJ phase quasi‐2D perovskite@graphene in realizing stable, sensitive, and spectrally tunable PDs.

Single-Source VLCP System Based on Solar Cell Array Receiver and Right-Angled Tetrahedron Trilateration VLP (RATT-VLP) Algorithm

A significant deployment limitation for visible light communication and positioning (VLCP) systems in energy- and light-source-restricted scenarios is the reliance of photodetectors (PDs) on external power supplies, compromising sustainability and complicating receiver charging. Solar cells (SCs), capable of harvesting and converting environmental light into electrical energy, offer a promising alternative. Consequently, we first propose an indoor VLCP system that utilizes an SC array as the receiver, alongside a right-angled tetrahedron trilateration visible light positioning (RATT-VLP) algorithm based on a single light source and multiple receivers. The proposed system uses an SC array in place of PDs, utilizing binary phase shift keying (BPSK) signals for simultaneous communication and positioning. In experiments, we verified the system’s error-free communication rate of 1.21 kbps and average positioning error of 3.40 cm in a 30 cm × 30 cm area, indicating that the system can simultaneously satisfy low-speed communication and accurate positioning applications. This provides a viable foundation for further research on SC-based VLCP systems, facilitating potential applications in environments like underwater wireless communication, positioning, and storage tank inspection.

Construction of g-C3N4/SnSe2/H-TiO2 Ternary Heterojunction for High-Performance Photodetectors

Two-dimensional layered materials have been widely used in the field of photodetectors because of their unique photoelectric properties. Among them, the multi-heterojunction based on two-dimensional materials with high carrier separation efficiency is expected to be designed as a high-performance photodetector (PD). This work focuses on the fabrication of g-C3N4/SnSe2/H-TiO2 ternary heterojunctions for photodetectors, obtained by depositing SnSe2 and g-C3N4 nanosheets onto TiO2 nanotube arrays using chemical vapor deposition and impregnation methods, respectively. The formation of the g-C3N4/SnSe2/H-TiO2 ternary heterojunction enhances and broadens absorption in the ultraviolet-visible range. Photoelectrochemical measurements have confirmed that the fabricated g-C3N4/SnSe2/H-TiO2 ternary heterojunction photodetector exhibits remarkable light detection capabilities at 370, 450, and 520 nm, meaning broadband photodetection behavior. Notably, under light illumination of 370 nm wavelength, it demonstrates a high responsivity of 2.742 A W−1, an impressive detectivity of 5.84 × 1010 Jones, an external quantum efficiency of 9.21 × 102 %, and excellent stability. This high performance can be attributed to the effective separation and transfer of photogenerated carriers within the ternary heterojunction, significantly enhancing the photoresponse. The construction of the novel broadband-responsive ternary g-C3N4/SnSe2/TiO2 heterojunction holds promise for driving the future development of wideband, high-performance, and highly integrated photodetectors.

Enhancing the Quality of MOF Thin Films for Device Integration Through Machine Learning: A Case Study on HKUST‐1 SURMOF Optimization

AbstractMetal–organic Frameworks (MOFs), especially as thin films, are increasingly recognized for their potential in device integration, notably in sensors and photo detectors. A critical factor in the performance of many MOF‐based devices is the quality of the MOF interfaces. Achieving MOF thin films with smooth surfaces and low defect densities is essential. Given the extensive parameter space governing MOF thin film deposition, the use of machine learning (ML) methods to optimize deposition conditions is highly beneficial. Combined with robotic fabrication, ML can more effectively explore this space than traditional methods, simultaneously varying multiple parameters to improve optimization efficiency. Importantly, ML can provide deeper insights into the synthesis of MOF thin films, an essential area of research. This study focuses on refining an HKUST‐1 SURMOF (surface‐mounted MOF) to achieve minimal surface roughness and high crystallinity, including a quantitative analysis of the importance of the various synthesis parameters. Using the SyCoFinder ML technique, thin film surface quality is markedly enhanced in just three generations created by a genetic algorithm, covering 30 distinct parameter sets. This method greatly reduces the need for extensive experimentation. Moreover, the results enhance the understanding of the vast synthesis parameter space in HKUST‐1 SURMOF growth and broaden the applications of MOF thin films in electronic and optoelectronic devices.

Development of a broadband photodetector utilizing ZnO nanorods with grating structure fabricated via nanoimprint lithography

Nanoimprint lithography (NIL) has emerged as a powerful technique for integrating nanostructures into semiconductor devices, particularly optoelectronic devices such as solar cells, light-emitting diodes (LEDs), lasers, and photodetectors (PDs). This study presents the successful fabrication of nano-patterned ZnO nanorods (ZnO NRs) using NIL, resulting in a grating structure with a linewidth of approximately 600 nm and a periodicity of around 1080 nm. Morphological characterizations, including scanning electron microscopy (SEM), atomic force microscopy (AFM), and laser confocal microscopy, reveal well-defined grating structures with ZnO NRs deposited on the substrate. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) further confirm the crystallinity of ZnO NRs, both with and without NIL treatment. X-ray photoemission spectroscopy (XPS) shows that the NIL-patterned samples with ZnO NRs exhibit fewer defects, attributed to the O2 plasma treatment during the NIL process. The NIL-defined grating structure of ZnO NRs is then employed in the fabrication of photodetectors, which demonstrate higher sensitivity than the pure ZnO-NRs-based PDs, presumably due to the reduce defects. Moreover, the NIL-defined PDs exhibit broadband photoresponses across the UV and visible light spectrum. This work introduces a novel device design for photodetectors and highlights the potential of NIL in creating broadband ZnO-based PDs, promising applications in future optoelectronics.

Realization of CO2 gas sensors and broadband photodetectors using metal/high-k CeO2/p-Si heterojunction

Realization of high-k dielectric oxide material-based devices such as photodetectors (PDs)/gas sensors fabricated on silicon substrate seems to be the utmost promising as a cost-effective approach to use in next generation optoelectronic field. We have explored metal/CeO2/p-Si heterojunction to construct as a broadband (BB) PD and CO2 gas sensor device. The effect of post-annealing procedure on photodetection and CO2 gas sensing characteristics were correlated using AFM, XRD, XPS, Raman and UV–Vis studies. At 0 V bias, the fabricated as-deposited Au/CeO2/p-Si PD device exhibits outstanding performance with enhanced responsivity of 85 AW−1 (at 910 nm), detectivity of 1.36×1015 Jones (at 850 nm), EQE of 1.3×104 % (at 850 nm), faster rise and fall times of 124 ms and 107 ms (at 900 nm). On the other hand, the photodetection characteristic parameters were slightly deteriorated as a function of annealing with respect to the as-deposited device. One of the causes for this fact was attributed to the increase in rms surface roughness (AFM) and decrease in absorbance of CeO2 thin film (UV–Vis). Additionally, Ag/CeO2/p-Si heterojunction was studied as a CO2 gas sensor and evaluated response/recovery times as a function of CO2 gas concentration. Sensing responses of CeO2 as-deposited, CeO2-400, CeO2-500, CeO2-600 and CeO2-700 °C were around 58, 60, 62, 81 and 90 %, respectively, when exposed to 200 ppm of CO2. Thus, we validate that the prospect of integrating enhanced performance in BB PDs and CO2 gas sensors using metal/CeO2/p-Si heterojunction could serve as a basic building block in near future optoelectronic applications. Furthermore, the effect of post-annealing temperature on the morphological, structural, BB photodetection and CO2 gas sensing properties were discussed in detail.