Optoelectronic device for detecting a gas

Abstract

An optoelectronic device for detecting a gas is specified. According to one embodiment, the optoelectronic device (1) for detecting a gas (9) comprises a radiation-emitting element (4) configured for emitting an electromagnetic radiation (10), a measurement unit (5) comprising a measurement region (51) and a reference region (52), and a detector unit (6) comprising at least a first photodetector region (61) and a second photodetector region (62), wherein the measurement region (51) is arranged in a first beam path of the electromagnetic radiation (10) between the radiation-emitting element (4) and the first photodetector region (61), wherein the reference region (52) is arranged in a second beam path of the electromagnetic radiation (10) between the radiation-emitting element (4) and the second photodetector region (62), wherein the first beam path and the second beam path are reflective, and wherein the optoelectronic device (1) is surface mountable. In particular, the radiation-emitting element (4) comprises a micro-LED.

Description

[0001] Description

[0002] OPTOELECTRONIC DEVICE FOR DETECTING A GAS

[0003] An optoelectronic device for detecting a gas is speci fied .

[0004] It is an obj ect to provide a compact optoelectronic device for detecting a gas .

[0005] An optoelectronic device for detecting a gas is speci fied . In particular, the optoelectronic device is configured for detecting the presence of a gas by using electromagnetic radiation . For example , a change of an intensity, a wavelength, a frequency and / or a polari zation of the electromagnetic radiation is detectable in the presence of the gas . In particular, a level of the change depends on an amount of the gas present . For example , i f more gas is present , the change will be more pronounced . For instance , the optoelectronic device for detecting a gas is configured for detecting a gas in a concentration of between and including 0 . 01 % and 4 % . In particular, the optoelectronic device is a gas sensor . For example , the gas is hydrogen (H2) or ammonia (NH3) or a harmful gas such as SOXor NOX.

[0006] According to at least one embodiment , the optoelectronic device comprises a radiation-emitting element configured for emitting an electromagnetic radiation . In particular, the radiation-emitting element is a radiation-emitting diode such as a light-emitting diode ( LED) . Alternatively, the radiation-emitting element can be a surface emitting laser such as a vertical cavity surface emitting laser (VCSEL ) or an edge emitting laser . Here and in the following, the terms light and electromagnetic radiation are used interchangeable . In particular, the electromagnetic radiation comprises a wavelength or a wavelength range of the ultraviolet (UV) wavelength range , the visible (VIS ) wavelength range and / or the infrared ( IR) wavelength range . For example , the electromagnetic radiation is radiation in the infrared wavelength range . In particular, the electromagnetic radiation comprises a wavelength or a wavelength range between and including 1100 nm and 1500 nm, for example between and including 1200 nm and 1400 nm or between and including 1250 nm and 1350 nm, for instance between and including 1280 nm and 1300 nm . Alternatively, the electromagnetic radiation can comprise a wavelength or a wavelength range between and including 800 nm and 900 nm .

[0007] According to at least one embodiment , the optoelectronic device comprises a measurement unit comprising a measurement region and a reference region . In particular, the measurement unit is configured for detecting the gas . For example , the measurement region of the measurement unit is configured for interacting with the gas , for instance binding the gas to the measurement region . In particular, the reference region is configured for not interacting with the gas .

[0008] According to at least one embodiment , the optoelectronic device comprises a detector unit comprising at least a first photodetector region and a second photodetector region . In particular, each photodetector region is configured for detecting an electromagnetic radiation incident on the respective photodetector region . For example , each photodetector region is configured for detecting an intensity, a wavelength, a frequency, and / or a polari zation of the incident electromagnetic radiation . In particular, the first photodetector region and the second photodetector region are operable independently of one another . For example , the first photodetector region comprises or consists of a first photodiode and the second photodetector region comprises or consists of a second photodiode . Alternatively, the first photodetector region can be a first part of a two- part photodiode and the second photodetector region can be a second part of the two-part photodiode . The photodetector unit can comprise a plurality of photodetector regions . For example , the photodetector unit can comprise a plurality of first photodetector regions and a plurality of second photodetector regions .

[0009] According to at least one embodiment , the measurement region is arranged in a first beam path of the electromagnetic radiation between the radiation-emitting element and the first photodetector region . In particular, the first beam path is a path of at least a part of the electromagnetic radiation starting from the radiation-emitting element and ending at the first photodetector region . In other words , the first photodetector region is configured for detecting a measurement signal .

[0010] According to at least one embodiment , the reference region is arranged in a second beam path of the electromagnetic radiation between the radiation-emitting element and the second photodetector region . In particular, the second beam path is a path of at least a part of the electromagnetic radiation starting from the radiation-emitting element and ending at the second photodetector region . In other words , the second photodetector region is configured for detecting a reference signal . In particular, the first beam path and the second beam path are independent of one another . For example , the first beam path and the second beam path are separate beam paths . The first beam path and the second beam path can be parallel to one another . For instance , the first beam path and the second beam path do not overlap .

[0011] According to at least one embodiment , the first beam path and the second beam path are reflective . In particular, for measuring the measurement signal and the reference signal , electromagnetic radiation is used that is reflected as it passes along the first beam path or the second beam path, respectively . For example , the electromagnetic radiation is reflected in the measurement unit , in particular in the measurement region or the reference region, respectively . For instance , at least 80 % , in particular at least 90 % , of the electromagnetic radiation entering the measurement unit is reflected inside the measurement unit .

[0012] In particular, the first beam path is configured in such a way that the electromagnetic radiation enters the measurement region from a side facing the radiation-emitting element , is at least partially reflected inside the measurement region, and exits the measurement region on the side facing the radiation-emitting element . In other words , the measurement of the measurement signal is performed in reflection .

[0013] In particular, the second beam path is configured in such a way that the electromagnetic radiation enters the reference region from a side facing the radiation-emitting element , is at least partially reflected inside the reference region, and exits the reference region on the side facing the radiationemitting element . In other words , the measurement of the reference signal is performed in reflection . In particular, the reflection of the electromagnetic radiation is specular or di f fuse . A specular reflection can be achieved by a smooth or smoothed surface . A di f fuse reflection can be achieved by a rough or roughened surface . The smooth or smoothed surface or the rough or roughened surface can be a part of the measurement unit , in particular of the measurement region or the reference region, respectively .

[0014] According to at least one embodiment , the optoelectronic device is surface mountable . A surface mountable optoelectronic device is , in particular, directly mountable onto the surface of a printed circuit board ( PCB ) . For example , the optoelectronic device is referred to as a surface-mount device ( SMD) . Here and in the following, mountable or mounted components or devices are attachable or attached to an underlying surface such as a substrate , a housing, or a printed circuit board . The components or devices can be attached by a connection mean such as a soldered contact or an adhesive layer . In particular, the optoelectronic device for detecting a gas is designed as a surface mountable package . For example , the optoelectronic device is a gas sensor designed as a surface mountable package .

[0015] According to at least one embodiment , the optoelectronic device comprises a radiation-emitting element configured for emitting an electromagnetic radiation, a measurement unit comprising a measurement region and a reference region, and a detector unit comprising at least a first photodetector region and a second photodetector region, wherein the measurement region is arranged in a first beam path of the electromagnetic radiation between the radiation-emitting element and the first photodetector region, wherein the reference region is arranged in a second beam path of the electromagnetic radiation between the radiation-emitting element and the second photodetector region, wherein the first beam path and the second beam path are reflective , and wherein the optoelectronic device is surface mountable .

[0016] It is an idea of the present application to provide a surface mountable optoelectronic device for detecting a gas comprising all components of a gas detecting system in a compact design . The optoelectronic device is simple and costef ficient . The measurement unit having a measurement region and a reference region has an uncomplicated and thus insensitive design and, due to the reference region, allows a reference measurement . The reference measurement can be performed automatically without using valves or reference gases or reference chambers . This can advantageously increase the length of use and the li fetime of the optoelectronic device . Due to the reference measurement , the measurement for detecting the gas is independent of factors such as a color or a spectral composition of the radiation-emitting element which can change during the li fetime of the radiationemitting element , for example , due to deposition of dust on the radiation-emitting element . Thus , it is advantageous to base the measurement on a relative measurement result determined by comparing the measurement signal and the reference signal instead of only using the absolute value of the measurement signal . In other words , the optoelectronic device allows to detect a relative change in the measurement signal compared to the reference signal . The measurement result is thus independent of the absolute intensities detected by the photodetector regions . Further, the reference measurement suppresses disturbance variables and improves the signal-to-noise ratio . The signal-to-noise ratio is further improved by using a first photodetector region for providing the measurement signal and a second photodetector region for providing the reference signal . As the measurement unit can reflect a large amount of the electromagnetic radiation that enters the measurement unit such as at least 80 % , the power consumption of the optoelectronic device can advantageously be decreased and a sensitivity of the optoelectronic device can be increased by using reflective beam paths .

[0017] According to at least one embodiment , the optoelectronic device comprises a substrate . In particular, the substrate is configured for providing a support and / or mounting the components of the optoelectronic device such as the radiation-emitting element and the detector unit . For example , the substrate is a SMT-substrate . Here and in the following, SMT is the abbreviation for surface mount technology . In particular, a SMT-substrate only comprises solderable connection surfaces or solderable connection pins for connecting the SMT substrate to , for example , a printed circuit board . In other words , the SMT-substrate is free of wire bonds . A SMT-substrate can advantageously be provided cost-ef f iciently . An optoelectronic device comprising a SMT- substrate is advantageously easy to install , in particular easy to integrate into a control system such as a control system of a heating system .

[0018] According to at least one embodiment , electrical connection pads of the optoelectronic device are exclusively arranged on the side of the substrate facing away from the radiationemitting element , the measurement unit , and the detector unit . In particular, all electrical connection pads of the optoelectronic device are arranged on one side of the substrate , wherein the components of the optoelectronic device such as the radiation-emitting element , the measurement unit , and the detector unit are arranged on the opposite side of the substrate . A substrate having electrical connection pads exclusively facing away from the components of the optoelectronic device can advantageously be surface mounted simply and ef ficiently .

[0019] According to at least one embodiment , the gas is hydrogen . Hydrogen gas is used as a fossil- free energy carrier, for example as hydrogen fuel . Hydrogen gas is highly flammable and forms explosive mixtures with air . The explosive reactions may be triggered by spark, heat , or sunlight . Thus , for a safe introduction and distribution of hydrogen gas for private mobility and home technology such as heating or energy storage , cost-ef ficient hydrogen sensors are needed . A simple and cost-ef ficient optoelectronic device for detecting hydrogen in a compact design can advantageously be used for increasing the safety of such applications .

[0020] According to at least one embodiment , the optoelectronic device comprises a housing . The housing is configured for protecting the components of the optoelectronic device such as the radiation-emitting element , the measurement unit , and the detector unit against damage , in particular, by providing a protective barrier against external influences such as a deposition of dust on sensitive surfaces of the components . In particular, the housing is impermeable to the electromagnetic radiation emitted by the radiation-emitting element . In this instance , the environment surrounding the optoelectronic device is protected against the electromagnetic radiation emitted by the radiation-emitting element . Further, the optoelectronic device , in particular the detector unit , is protected against electromagnetic radiation from external radiation sources located outside the optoelectronic device . The housing can further be impermeable to electromagnetic radiation having a di f ferent wavelength or wavelength range than the electromagnetic radiation emitted by the radiation-emitting element . A housing, in particular a radiation-impermeable housing, can advantageously improve the signal-to-noise ratio and suppress disturbance variables .

[0021] According to at least one embodiment , the housing is formed by inj ection molding . An inj ection molded housing is stable and can advantageously be provided cost-ef f iciently .

[0022] According to at least one embodiment , the substrate and the housing surround a volume , in particular completely . In particular, the volume is a three-dimensional space surrounded by side surfaces . The substrate can cover a side surface of the volume and the housing can cover the remaining side surfaces of the volume . For example , the volume is completely surrounded by the substrate and the housing in such a way that electromagnetic radiation, in particular at least electromagnetic radiation having the wavelength or the wavelength range emitted by the radiation-emitting element , from external light sources cannot enter the volume . Surfaces of the housing facing towards the volume can be referred to as inside surfaces of the housing .

[0023] According to at least one embodiment , the radiation-emitting element , the measurement unit , and the detector unit are arranged in the volume . In particular, the radiation-emitting element , the measurement unit , and the detector unit are mounted on the substrate and / or on inside surfaces of the housing within the volume . Thus , a compact design of the optoelectronic device can advantageously be reali zed .

[0024] According to at least one embodiment , the housing comprises a gas inlet . In particular, the gas inlet is configured for providing the gas within the volume . For example , the gas inlet is an opening in the housing through which the gas can flow into the volume . For instance , the gas inlet can be arranged in or be a side of the housing opposite of the substrate . In this instance , a part of the side of the housing or the entire side of the housing can be free of a material of the housing . A gas inlet is a simple way for providing the gas within the volume . Alternatively, the gas inlet can be an opening in the housing through which the gas can come into contact with the measurement unit . In this instance , the volume can be free of the gas .

[0025] According to at least one embodiment , the gas inlet is covered with a covering impermeable to the electromagnetic radiation emitted by the radiation-emitting element . In particular, the covering is permeable for the gas . In other words , the gas can pass through the covering, whereas electromagnetic radiation having at least the wavelength or the wavelength range of the electromagnetic radiation emitted by the radiation-emitting element cannot pass through the covering . For example , the covering is impermeable for an external electromagnetic radiation from radiation sources outside the optoelectronic device , in particular external electromagnetic radiation having at least the wavelength or the wavelength range emitted by the radiation-emitting element . A covering on the gas inlet can advantageously be stable and provide a protection against an interfering influence of external electromagnetic radiation . According to at least one embodiment , the covering comprises a meander perforated plate , an inverse opal layer, a foamed plastic layer, or at least three layers of a perforated metal sheet .

[0026] For example , a meander perforated plate comprises pores through the plate that are not straight , but bend . In this instance , gas can pass through the pores in the meander perforated plate , whereas the meander perforated plate is impermeable for electromagnetic radiation .

[0027] For example , an inverse opal layer comprises a regular arrangement of spherical void spaces surrounded by solid walls . The inverse opal layer is produced, for instance , by sel f-assembling a sacri ficial material such as polystyrene spheres , depositing a metal such as nickel or copper in the void spaces between the sacri ficial material , and removing the sacri ficial material to leave a three-dimensionally ordered porous solid .

[0028] For example , the foamed plastic layer comprises a plastic material having pores permeable for the gas . The plastic material can be a thermoplastic resin such as polycyclohexylenedimethylene terephthalate ( PCT ) , polybutylene terephthalate ( PBT ) , or polyphthalamide ( PPA) or a thermosetting resin such as epoxy . Thermoplastic resins and thermosetting resins can advantageously be stable at temperatures required for SMT-mounting of the optoelectronic device , for example for SMT-mounting with SnAgCu at 260 ° C . The foamed plastic layer can be produced by foam inj ection molding thereby producing a foam structure comprising the pores . In particular, the foam structure is present on all sides and intrinsically . The pores can be incorporated in the plastic material by physical methods such as in introduction of gas cavities in liquid plastic or chemical methods such as a gas production at elevated temperatures by a chemical reaction . For example , sodium carbonate is used in the chemical methods .

[0029] For example , the at least three layers of a perforated metal sheet are arranged on top of one another in such a way that openings of a layer partially overlap with openings of directly adj acent layers in such a way that there is no overlap of openings of three directly adj acent layers . For instance , openings of a first layer overlap with openings of a second layer and openings of the second layer overlap with openings of a third layer, but openings of the second layer do not overlap with openings of the first layer and the third layer at the same time . As a result , gas can permeate the covering, whereas electromagnetic radiation cannot permeate the covering . For example , the covering can comprise more than three layers of a perforated metal sheet such as four layers or five layers . In particular, the at least three layers of the perforated metal sheet are bonded to one another by means of adhering, soldering, or sintering . In these instances , an adhesive , a solder material , or a sintering material , respectively, are applied on the perforated metal sheets that are subsequently used to bond the layers together, for example by means of an elevated temperature . Alternatively, tinned metal sheets can be used and a further adhesive , solder material or sintering material can be dispensed with . Alternatively, the perforated metal sheets can be bonded by means of welding, in particular spot welding, for example laser spot welding or electrode spot welding . In this instance , the layer can be spot welded at every tenth location at which all layers are present .

[0030] According to at least one embodiment , the detector unit comprises an integrated circuit . In particular, the integrated circuit is configured for controlling the optoelectronic device , in particular the radiation-emitting element , for signal processing of the measurement signal and the reference signal , and for outputting a measurement result . Signal processing can include an analysis of the measurement signal and the reference signal and a determination of the measurement result . In particular, the integrated circuit is a monolithic integrated circuit . For example , the integrated circuit is an application-speci fic integrated circuit (AS IC ) . For instance , the first photodetector region and the second photodetector region are both arranged on a surface of the integrated circuit . An integrated circuit can advantageously combine the optical measurement and the signal processing in one compact optoelectronic device . Using a cost-ef ficient and standardi zed integrated circuit advantageously facilitates the integration of the optoelectronic device in a control system of , for example , a heating system .

[0031] According to at least one embodiment , the first photodetector region and the second photodetector region are arranged separately from the integrated circuit . In particular, the detector unit is formed of two parts , wherein a first part comprises the first photodetector region and the second photodetector region and a second part comprises the integrated circuit . Alternatively, the detector unit is formed of three parts , wherein a first part comprises the first photodetector region, a second part comprises the second photodetector region, and a third part comprises the integrated circuit .

[0032] According to at least one embodiment , the measurement region and / or the reference region comprises a transparent plate , a measurement stack, and a protective layer . The measurement stack is arranged between the transparent plate and the protective layer . In particular, the transparent plate , the measurement stack, and the protective layer are arranged in such a way that the transparent plate and the protective layer are in direct mechanical contact in a region laterally surrounding the measurement stack . Thus , the measurement stack is surrounded by the transparent plate and the protective layer from all sides .

[0033] In particular, the transparent plate is transparent for the electromagnetic radiation emitted by the radiation-emitting element . For example , the transparent plate is impermeable for the gas . For instance , the transparent plate is a glass plate .

[0034] In particular, the measurement stack is configured for interacting with the gas . For example , gas molecules bind to and / or chemically react with the material of the measurement stack . The binding and / or chemical reaction can cause a change of a transmission of the electromagnetic radiation through the measurement region of the measurement unit . In particular, the measurement stack comprises or consists of a metal or metal alloy . For example , the measurement stack comprises or consists of a magnesium alloy such as a Pd-capped Mg82Tii8alloy, a Mg82Zri8alloy, a Pd-capped YsoMgso alloy, a tantalum palladium alloy such as Tao. gPdo. i , or a palladium gold copper alloy such as Pdo.5Auo.35Cuo. o5 • In the case of the gas being hydrogen, hydrogen reacts with a metal that is present in the measurement stack thereby forming metal hydrides . The metal hydrides can absorb a part of the electromagnetic radiation of the first beam path thereby, for example , changing the intensity of the measurement signal . In particular, the formation of metal hydrides changes a transparency of the measurement region depending on the amount of hydrogen gas present in the optoelectronic device .

[0035] In particular, the measurement stack comprises at least one measurement layer . For example , the measurement stack comprises one measurement layer, two measurement layers or more than two measurement layers . Here and in the following, measurement layers are layers of the measurement stack, in particular metal layers or metal alloy layers , without protective layers . It is possible that not all materials suitable for the measurement stack adhere equally well to one another and / or to the transparent plate and / or the protective layer . By using at least one measurement layer in the measurement stack, an adhesion of the components and layers of the measurement unit can advantageously be enhanced and tailored to speci fic applications .

[0036] For example , the measurement stack comprises at least a first measurement layer and a second measurement layer arranged between the first measurement layer and the protective layer . For example , the first measurement layer and the second measurement layer comprise or consist of a metal or a metal alloy . For instance , the metal alloy is a tantalum palladium alloy such as Tao . gPdo . i or a palladium gold copper alloy such as Pdo. eAuo. ssCuo. os • A measurement stack comprising a first measurement layer of a tantalum palladium alloy such as Tao . gPdo . i and a second measurement layer of a palladium gold copper alloy such as Pdo. eAuo.35Cuo. o5 is advantageously suited for detecting hydrogen gas .

[0037] In particular, the protective layer is configured for protecting the measurement stack against damage . For example , the protective layer is permeable for the gas , in particular for hydrogen . Thus , during operation of the optoelectronic device , the measurement region comes into contact to the gas . The gas can pass through the protective layer to reach the measurement stack in the measurement region . The gas can interact with the measurement stack and create a measurement signal at the first photodetector region . For example , the protective layer comprises or consists of polytetrafluoroethylene ( PTFE ) . PTFE can advantageously provide an improved gas selectivity for hydrogen gas .

[0038] According to at least one embodiment , the reference region further comprises a gas-impermeable layer . The gas- impermeable layer is arranged between the measurement stack and the protective layer . In other words , the reference region comprises the transparent plate , the measurement stack, the gas-impermeable layer, and the protective layer in this order . For instance , the gas-impermeable layer comprises or consists of silicon dioxide ( SiCy ) .

[0039] In particular, the gas-impermeable layer is configured in such a way that the gas passes through the gas-impermeable layer signi ficantly slower than through the protective layer . It should be noted that the gas-impermeable layer may not be completely impermeable for the gas . However, a gas transport through the gas-impermeable layer is very slow compared to any layers described herein as gas-permeable . For example , the transparent plate , the measurement stack, and the gas- impermeable layer are arranged in such a way that the transparent plate and the gas-impermeable layer are in direct mechanical contact in a region laterally surrounding the measurement stack . Thus , the measurement stack is surrounded by the transparent plate and the gas-impermeable layer from all sides . During operation of the optoelectronic device , the reference region comes into contact to the gas . However, due to the gas-impermeable layer, the gas cannot pass through the gas-impermeable layer and through the transparent plate at a first contact of the gas to the reference region . Thus , the gas cannot reach the measurement stack in the reference region at the same time that the gas reaches the measurement stack in the measurement region . Thus , i f a gas comes into contact with the measurement unit for the first time , the measurement signal is di f ferent from the reference signal and the optoelectronic device determines a measurement result that indicates the presence of the gas . A reference region with a gas impermeable layer advantageously allows to perform reference measurements and thus increase the signal-to-noise ratio .

[0040] In particular, the reference region only di f fers from the measurement region in the presence of the gas-impermeable layer . Thus , the electromagnetic radiation passes through a similar layer stack along the first beam path and along the second beam path . This advantageously ensures a more accurate measurement result .

[0041] According to at least one embodiment , the measurement region and / or the reference region further comprises a cover layer . The cover layer is arranged on a side of the protective layer facing away from the measurement stack . In particular, the cover layer is impermeable for electromagnetic radiation emitted by the radiation-emitting element and for electromagnetic radiation having a di f ferent wavelength or wavelength range . For example , the cover layer is not transparent for electromagnetic radiation in the UV wavelength range and / or visible wavelength range and / or IR wavelength range . For instance , the cover layer comprises or consists of a black thin plastic layer . The black thin plastic layer can have a thickness of at least 1 pm and at most 10 pm . For example , the thin black plastic layer comprises black sooty particles dispersed in an epoxy layer or a silicone layer . Alternatively, the cover layer comprises or consists of porous silicon . Alternatively, the cover layer can be a platelet of a material of the covering described above . The platelet can be bonded to the protective layer by means of an adhesive . A cover layer can advantageously be used as an alternative for a radiation-impermeable housing or as an alternative for a covering for the gas inlet .

[0042] According to at least one embodiment , the transparent plate is arranged on a side of the measurement region and / or the reference region facing the radiation-emitting element and the detector unit . In particular, the gas inlet is arranged on a side of the measurement region and / or the reference region facing away from the transparent plate . As a result , the gas can come into contact with the measurement stack by passing through the gas-permeable protective layer in the measurement region . Such a configuration advantageously allows to detect the gas simply and fast . In addition, the electromagnetic radiation can enter the measurement unit through the transparent plate and can come into contact with the measurement stack without any intervening layers or plates capable of absorbing electromagnetic radiation . Thus , the sensitivity of the optoelectronic device can advantageously be increased .

[0043] According to at least one embodiment , the measurement region and / or the reference region are arranged in the gas inlet of the housing, and the cover layer forms the covering . In particular, the measurement region and / or the reference region are mounted on inside surfaces of the housing, for example via the transparent plate . For instance , the transparent plate faces the radiation-emitting element and the detector unit . In other words , the cover layer forms an outside surface of the housing . By integrating the covering in the measurement region and / or the reference region as the cover layer, an additional mounting of a covering can be dispensed with and the optoelectronic device can advantageously be produced simply and cost-ef f iciently .

[0044] According to at least one embodiment , the measurement region and the reference region are arranged directly adj acent to one another . In particular, the measurement region and the reference region share the same transparent plate . In this case , the measurement unit is formed as one component . The measurement stack can be formed as a two-part measurement stack with the two parts arranged directly adj acent to one another on the same transparent plate . One of the two parts can form the measurement region and the other part can form the reference region . The protective layer can also be formed as a two-part protective layer or as one protective layer covering both parts of the two-part measurement stack . The reference region further comprises the gas-impermeable layer . The first photodetector region and the second photodetector region can also be arranged directly adj acent to one another . For example , the first beam path and the second beam path are parallel to one another . A measurement unit having the measurement region and the reference region directly adj acent to one another can advantageously be produced and mounted easily and cost-ef f iciently .

[0045] According to at least one embodiment , the measurement region and the reference region are arranged on di f ferent sides of the radiation-emitting element . In other words , the radiation-emitting element is arranged between the measurement region and the reference region . In particular, the measurement region and the reference region are arranged directly adj acent to one another on the same transparent plate in such a way that the measurement region is above one side of the radiation-emitting element and the reference region is above the other side . In particular, the first photodetector region and the second photodetector region are also arranged on di f ferent sides of the radiation-emitting element such that electromagnetic radiation of the first beam path that is reflected inside the measurement region impinges on the first photodetector region and electromagnetic radiation of the second beam path that is reflected inside the reference region impinges on the second photodetector region .

[0046] According to at least one embodiment , the optoelectronic device further comprises a structure for optically separating the radiation-emitting element and the detector unit at least partially . In particular, the structure is a blocking element configured for blocking a direct beam path of electromagnetic radiation between the radiation-emitting element and the detector unit . For example , the blocking element can be a radiation blocker implemented into the housing or a radiation blocker laterally surrounding the radiation-emitting element . For instance , the blocking element can have a height perpendicular to the main extension direction of the radiation-emitting element or the detector unit of at most three times , in particular at most twice , a height of the radiation-emitting element . A structure for optically separating the radiation-emitting element and the detector unit can advantageously ensure that no or no signi ficant amount of electromagnetic radiation from the radiationemitting element directly impinges on the detector unit . Thus , the sensitivity of the optoelectronic device can be signi ficantly increased .

[0047] According to at least one embodiment , the detector unit is mounted on the substrate . In particular, the first photodetector region and / or the second photodetector region are arranged in the detector unit on a side of the detector unit facing away from the substrate . For example , the integrated circuit of the detector unit is mounted on the substrate and the first photodetector region and the second photodetector region are arranged on a side of the integrated circuit facing away from the substrate . By mounting the detector unit on the substrate , electrical contacts to the detector unit can advantageously easily be established through the substrate .

[0048] According to at least one embodiment , the radiation-emitting element is mounted on the substrate . In particular, the radiation-emitting element and the detector unit are mounted on the substrate . By mounting the radiation-emitting element on the substrate , electrical contacts can advantageously be established easily through the substrate and the optoelectronic device can advantageously be provided simply and cost-ef f iciently . According to at least one embodiment , the radiation-emitting element is mounted on the detector unit . In particular, the radiation-emitting element is mounted on a part of the detector unit that is free of the photodetector regions , for example , on the integrated circuit . The first photodetector region and the second photodetector region can be arranged adj acent to one another . Alternatively, the first photodetector region and the second photodetector region can be spaced apart , for example , on di f ferent sides of the radiation-emitting element . For example , the radiationemitting element is electrically contacted through the substrate and the detector unit , in particular through the substrate and the integrated circuit of the detector unit . By mounting the radiation-emitting element on the detector unit , electrical contacts can advantageously be established easily through the substrate and the detector unit . Thus , the optoelectronic device can advantageously be provided simply and cost-ef f iciently . Further, by mounting the radiationemitting element on the detector unit , the signal-to-noise ratio can advantageously be further improved .

[0049] According to at least one embodiment , the measurement unit is spaced apart from the radiation-emitting element and the detector unit . In particular, the measurement unit is mounted on inside surfaces of the housing close to or in the gas inlet . For example , the gas inlet is arranged on a side of the housing opposite the substrate and the radiation-emitting element and the detector unit are mounted on the substrate . Alternatively, the detector unit is mounted on the substrate and the radiation-emitting element is mounted on the detector unit . In both instances , the measurement unit is arranged at the opposite side of the optoelectronic device with regard to the radiation-emitting element and the detector unit . This can advantageously ensure that the measurement unit is arranged in the first beam path and the second beam path .

[0050] According to at least one embodiment , the radiation-emitting element comprises or is a micro-LED . It is also possible that the radiation-emitting element comprises or is a mini-LED . As a broad definition, a micro-LED could be seen as any lightemitting diode ( LED) with a particularly small si ze . Micro- LEDs may comprise a width, a length, a thickness and / or a diameter smaller than or equal to 100 micrometers , in particular, smaller than or equal to 70 micrometers , for example smaller than or equal to 50 micrometers . In particular, micro-LEDs , for example rectangular micro-LEDs , have an edge length, in particular in plan view of the layers of the semiconductor layer sequence , of a luminous surface smaller than or equal to 70 micrometers , for example smaller than or equal to 50 micrometers . For example , a micro-LED is a light-emitting diode with a growth substrate removed, such that a thickness of the micro-LED is in the range between and including, for example , 1 . 5 micrometers and 10 micrometers . For example , the micro-LED is provided on a wafer having releasable retaining structures . The micro-LED can be detached from the wafer in a non-destructive manner .

[0051] In particular, micro-LEDs are used in optoelectronic devices to provide electromagnetic radiation depending on the speci fic application . The micro-LEDs can form pixels or subpixels and can emit electromagnetic radiation of a defined color or wavelength or wavelength range . Small pixel si ze and a high density with close distances make micro-LEDs suitable , among others , for optoelectronic devices such as gas sensors for consumer applications , industrial applications , and automotive applications , for instance in fuel cells .

[0052] Advantageous embodiments and developments of the optoelectronic device for detecting a gas will become apparent from the exemplary embodiments described below in conj unction with the figures .

[0053] In the figures :

[0054] Figures 1A, 4A, 5A and 6A each show a schematic sectional side view of an optoelectronic device for detecting a gas according to di f ferent exemplary embodiments ,

[0055] Figures IB, 4B, 5B and 6B each show a schematic top view of an optoelectronic device according to di f ferent exemplary embodiments ,

[0056] Figure 2A shows a schematic top view of a measurement unit according to an exemplary embodiment ,

[0057] Figures 2B to 2G each show a schematic sectional side view of a measurement unit according to di f ferent exemplary embodiments ,

[0058] Figure 3A and 3B each show a schematic sectional side view of a covering according to di f ferent exemplary embodiments ,

[0059] Figures 3C to 3E each show a schematic top view of a covering according to di f ferent exemplary embodiments .

[0060] In the exemplary embodiments and figures , similar or similarly acting constituent parts are provided with the same reference signs . The elements illustrated in the figures and their si ze relationships among one another should not be regarded as true to scale . Rather, individual elements may be represented with an exaggerated si ze for the sake of better representability and / or for the sake of better understanding .

[0061] The optoelectronic device 1 of the exemplary embodiment shown in figures 1A and IB is configured for detecting a gas 9 , for example hydrogen (H2) or ammonia (NH3) or a harmful gas such as S0xor N0x.

[0062] The optoelectronic device 1 is surface mountable . The optoelectronic device 1 comprises a substrate 2 , in particular a SMT-substrate , and a housing 3 , in particular an inj ection molded housing . Electrical connection pads 21 of the optoelectronic device 1 are arranged exclusively on a side of the substrate 2 facing away from the housing 3 . The housing 3 comprises a gas inlet 31 covered with a covering 32 . For example , the covering 32 can be mounted by means of an adhesive 33 . The gas inlet 31 is arranged on a side of the housing 3 opposite of the substrate 2 . The housing 3 as well as the covering 32 can be impermeable for electromagnetic radiation, in particular at least for an electromagnetic radiation 10 emitted by a radiation-emitting element 4 of the optoelectronic device 1 .

[0063] The substrate 2 and the housing 3 surround a volume 7 . Within the volume 7 , a radiation-emitting element 4 , a measurement unit 5 and a detector unit 6 are arranged . The radiationemitting element 4 and the detector unit 6 are mounted on and electrically contacted through the substrate 2 . The radiation-emitting element 4 is configured for emitting an electromagnetic radiation 10 , in particular, an electromagnetic radiation 10 in the ultraviolet wavelength range , the visible wavelength range , and / or the infrared wavelength range , for example , in the infrared wavelength range . The electromagnetic radiation 10 is emitted by the radiation exit surface 41 .

[0064] The detector unit 6 can comprise an integrated circuit 63 . On a side of the detector unit 6 , in particular of the integrated circuit 63 , facing away from the substrate 2 , a first photodetector region 61 and a second photodetector region 62 are arranged adj acent to one another . For example , the first photodetector region 61 comprises or consists of a first photodiode and the second photodetector region 62 comprises or consists of a second photodiode . Alternatively, the first photodetector region 61 can be a first part of a two-part photodiode and the second photodetector region 62 can be a second part of the two-part photodiode .

[0065] The measurement unit 5 is mounted on inside surfaces of the housing 3 , for example by means of an adhesive 33 . The measurement unit 5 is divided into a measurement region 51 and a reference region 52 . The measurement region 51 is arranged in a first beam path of the electromagnetic radiation 10 between the radiation-emitting element 4 and the first photodetector region 61 and the reference region 52 is arranged in a second beam path of the electromagnetic radiation 10 between the radiation-emitting element 4 and the second photodetector region 62 . In other words , in the exemplary embodiment of figures 1A and IB, the measurement region 51 is arranged above the radiation-emitting element 4 and the first photodetector region 61 and the reference region 52 is arranged above the radiation-emitting element 4 and the second photodetector region 62 . Both the first beam path and the second beam path are reflective . Thus , the measurement of a measurement signal via the first beam path and the measurement of a reference signal via the second beam path is performed in reflection as the electromagnetic radiation 10 of the radiation-emitting element 4 is at least partially reflected inside the measurement region 51 and the reference region 52 before it reaches the first photodetector region 61 or the second photodetector region 62 , respectively .

[0066] The measurement unit 5 comprises a transparent plate 53 and the measurement stack 54 arranged on a side of the transparent plate 53 facing away from the radiation-emitting element 4 and the detector unit 6 .

[0067] A structure 8 configured for optically separating the radiation-emitting element 4 and the detector unit 6 is arranged on the substrate 2 between the radiation-emitting element 4 and the detector unit 6 . The structure 8 is a blocking element for blocking a direct impingement of electromagnetic radiation 10 emitted by the radiationemitting element 4 on the detector unit 6 . The structure 8 is a radiation blocker implemented in the housing 3 .

[0068] During operation of the optoelectronic device 1 , the gas 9 enters the volume 7 through the gas inlet 31 and comes into contact with the measurement unit 5 . The gas 9 interacts with the measurement stack 54 in the measurement region 51 of the measurement unit 5 . For example , the gas 9 can bind to and / or chemically react with a material of the measurement stack 54 in the measurement region 51 . As a result , a property of the electromagnetic radiation 10 of the first beam path that is reflected in the measurement region 51 is changed . Thus , a measurement signal detected at the first photodetector region 61 is changed by the presence of the gas 9 in the volume 7 . In the reference region 52 , the gas 9 does not interact with the measurement stack 54 . Thus , a reference signal detected at the second photodetector region 62 remains unchanged by the presence of the gas 9 in the volume 7 . By comparing the measurement signal to the reference signal , a measurement result can be determined indicating the presence of the gas 9 as well as a concentration of the gas 9 due to the detected di f ference between the measurement signal and the reference signal .

[0069] The measurement unit 5 of the exemplary embodiment shown in figure 2A comprises a measurement region 51 and a reference region 52 . The measurement region 51 and the reference region 52 are arranged adj acent to one another . In the exemplary embodiment of figure 2A, the measurement region 51 and the reference region 52 share the same transparent plate 53 .

[0070] Figure 2B shows a schematic sectional side view of a measurement unit 5 of figure 2A. In the dashed circle denoted A ( in the following referred to as detail A) , figure 2B shows that a part of the transparent plate 53 laterally surrounding the measurement stack 54 is free of the measurement stack 54 .

[0071] Figures 2C to 2G each show a schematic sectional side view of detail A as illustrated in figure 2B according to di f ferent exemplary embodiments . Figures 2C, 2E , and 2G show measurement regions 51 , whereas figures 2D and 2 F show reference regions 52 of the measurement unit 5 . The measurement region 51 of the exemplary embodiment shown in figure 2C comprises a transparent plate 53 , a measurement stack 54 , and a protective layer 55 . The transparent plate 53 can be a glass plate . The measurement stack 54 is arranged between the transparent plate 53 and the protective layer 55 . In the exemplary embodiment of figure 2C, the measurement stack 54 comprises a first measurement layer 541 and a second measurement layer 542 arranged between the first measurement layer 541 and the protective layer 55 . The first measurement layer 541 and the second measurement layer 542 comprise or consist of a metal or metal alloy . For example , the first measurement layer 541 comprises or consists of a tantalum palladium alloy such as Tao. gPdo. i and the second measurement layer 542 comprises or consists of a palladium gold copper alloy such as Pdo. eAuo.35Cuo. o5 • For instance , such a measurement stack 54 is configured for detecting hydrogen gas . The protective layer 55 is arranged on the measurement stack 54 in such a way that it has a direct contact to the transparent plate 53 in a region of the transparent plate 53 that is free of the measurement stack 54 . Thus , the protective layer 55 and the transparent plate 53 surround the measurement stack 54 from all sides . The protective layer 55 is permeable for the gas 9 such that the gas 9 can penetrate the protective layer 55 and can come into contact with the measurement stack 54 in the measurement region 51 . For example , the protective layer 55 comprises or consists of polytetrafluoroethylene ( PTFE ) .

[0072] In contrast to the measurement region 51 shown in figure 2C, the reference region 52 of the exemplary embodiment shown in figure 2D further comprises a gas-impermeable layer 56 arranged between the measurement stack 54 and the protective layer 55 . The gas-impermeable layer 56 is arranged on the measurement stack 54 in such a way that it has a direct contact to the transparent plate 53 in the region of the transparent plate 53 that is free of the measurement stack 54 . Thus , the gas-impermeable layer 56 and the transparent plate 53 surround the measurement stack 54 from all sides and thus prevent that the gas 9 can reach the measurement stack 54 in the reference region 52 . For example , the gas- impermeable layer 56 comprises or consists of silicon dioxide ( SiO2) .

[0073] In contrast to the measurement region 51 shown in figure 2C, the measurement region 51 in figure 2E further comprises a cover layer 57 arranged on a side of the protective layer 55 facing away from the transparent plate 53 . The cover layer 57 can completely cover the protective layer 56 on a side of the protective layer 55 facing away from the measurement stack 54 . The cover layer 57 is permeable for the gas 9 and impermeable for electromagnetic radiation, in particular for electromagnetic radiation 10 emitted by the radiationemitting element 4 . The cover layer 57 can be used as an alternative for a radiation-impermeable housing 3 or as an alternative for a covering 32 for the gas inlet 31 . For example , the cover layer 57 is a black thin plastic layer or a layer comprising or consisting of porous silicon . The black thin plastic layer can comprise black sooty particles dispersed in an epoxy layer or a silicone layer .

[0074] Alternatively, the cover layer can be formed of a platelet of one of the materials for a covering 32 as described in conj unction with figures 3A to 3E . In this instance , the platelet is bonded to the protective layer 55 by means of an adhesive . In contrast to the reference region 52 shown in figure 2D, the reference region 52 in figure 2 F further comprises a cover layer 57 arranged on a side of the protective layer facing away from the transparent plate 53 . The cover layer 57 is identical to the cover layer described in conj unction with figure 2E .

[0075] In contrast to the measurement region 51 shown in figure 2E , the measurement region 51 of figure 2G comprises a transparent plate 53 having a side facing away from the measurement stack 54 that is grinded . Further, the side surfaces of the transparent plate 53 perpendicular to a main extension plane of the transparent plate 53 are diced and covered with both the protective layer 55 and the cover layer 57 . Having the cover layer 57 on the side surfaces of the transparent plate 53 improves the ef fect of the cover layer 57 as a transmission of electromagnetic radiation 10 through the side surfaces of the transparent plate 53 is reduced or prevented .

[0076] The covering 32 of the exemplary embodiment shown in figure 3A comprises a base material 321 having pores 322 . The covering 32 can be a meander perforated plate , a foamed plastic layer or an inverse opal layer .

[0077] The covering 32 of the exemplary embodiment shown in figure 3B comprises three layers 323 , 324 , 325 of a perforated metal sheet stacked above one another . All three layers comprise openings 3231 , 3241 , 3251 . The openings 3231 of the first layer 323 overlap with the openings 3241 of the second layer 324 and the openings 3251 of the third layer 325 overlap with the openings 3241 of the second layer 324 . However, the openings 3241 of the second layer 324 do not overlap with the openings 3231 , 3251 of the first layer and the third layer at the same time . Thus , the covering 32 is permeable for gas 9 and impermeable for electromagnetic radiation 10 . The layers 323 , 324 , 325 are bonded to one another by means of adhering, soldering, sintering, or welding .

[0078] Figure 3C shows an exemplary embodiment of a top view of the covering 32 of the exemplary embodiment shown in figure 3B . Figure 3C shows that the openings 3241 in the second layer 324 completely overlap with both openings 3231 , 3251 in the first layer 323 and the third layer 325 , but that the openings 3231 , 3251 in the first layer 323 and the third layer 325 have no overlap .

[0079] Figure 3D shows an alternative exemplary embodiment of a top view of the covering 32 of the exemplary embodiment shown in figure 3B . Figure 3D shows that the openings 3241 in the second layer 324 partially overlap with both openings 3231 , 3251 in the first layer 323 and the third layer 325 , but that the openings 3231 , 3251 in the first layer 323 and the third layer 325 have no overlap .

[0080] Figures 3E shows an alternative exemplary embodiment of a top view of a covering 32 comprising five layers of a perforated metal sheet . Figure 3 each shows an arrangement of the openings 3231 , 3241 , 3251 , 327 , 328 in which each opening partially overlaps with the openings of two other layers , in particular with any adj acent layers . However, there is no overlap of all openings such that the electromagnetic radiation 10 is not transmitted through the covering 32 , but the gas 9 can permeate the covering 32 . The optoelectronic device 1 of the exemplary embodiment shown in figures 4A and 4B corresponds essentially to the optoelectronic device 1 shown in figures 1A and IB . In contrast , the optoelectronic device 1 of figures 4A and 4B comprises no individual covering 32 . Instead, a measurement unit 5 as described in conj unction with figures 2E , 2 F, or 2G comprising a cover layer 57 is mounted in the gas inlet 31 of the housing 3 , for example , by means of an adhesive 33 . In other words , the cover layer 57 forms the covering 32 . Furthermore , the first photodetector 61 region and the second photodetector region 62 are arranged separately from the integrated circuit 63 .

[0081] The optoelectronic device 1 of the exemplary embodiment shown in figures 5A and 5B corresponds essentially to the optoelectronic device 1 shown in figures 1A and IB . In contrast , and as described in conj unction with figures 4A and 4B, the cover layer 57 forms the covering 32 . Furthermore , the radiation-emitting element 4 is mounted on the detector unit 6 , in particular on the integrated circuit 63 . In the exemplary embodiment of figures 5A and 5B, the first photodetector region 61 and the second photodetector region 62 are arranged on di f ferent sides of the radiation-emitting element 4 . In this instance , the measurement region 51 is arranged on a side of the measurement unit 5 that is arranged above the first photodetector region 61 and the reference region 52 is arranged on a side of the measurement unit 5 that is arranged above the second photodetector region 62 . The optoelectronic device 1 further comprises a structure 8 , in particular a radiation blocker, laterally surrounding the radiation-emitting element 4 . The optoelectronic device 1 of the exemplary embodiment shown in figures 6A and 6B corresponds essentially to the optoelectronic device 1 shown in figures 5A and 5B . In contrast , the radiation-emitting element 4 is mounted on the substrate 2 between the first photodetector region 61 and the second photodetector region 62 . In other words , the detector unit 6 is a two-part detector unit . Both parts of the detector unit 6 comprise an integrated circuit 63 . The optoelectronic device 1 shown in figure 6A and 6B is free of a structure 8 .

[0082] The features and exemplary embodiments described in connection with the figures can be combined with each other according to further exemplary embodiments , even i f not all combinations are explicitly described . Furthermore , the exemplary embodiments described in connection with the figures may have alternative or additional features as described in the general part .

[0083] This patent application claims the priority of German patent application 10 2024 100 859 . 8 , the disclosure content of which is hereby incorporated by reference .

[0084] The invention is not restricted to the exemplary embodiments by the description on the basis of said exemplary embodiments . Rather, the invention encompasses any new feature and also any combination of features , which in particular comprises any combination of features in the patent claims and any combination of features in the exemplary embodiments , even i f this feature or this combination itsel f is not explicitly speci fied in the patent claims or exemplary embodiments . References

[0085] 1 optoelectronic device

[0086] 2 substrate

[0087] 21 electrical connection pad

[0088] 3 housing

[0089] 31 gas inlet

[0090] 32 covering

[0091] 321 base material

[0092] 322 pores

[0093] 323 first layer

[0094] 3231 opening in first layer

[0095] 324 second layer

[0096] 3241 opening in second layer

[0097] 325 third layer

[0098] 3251 opening in third layer

[0099] 326 connection

[0100] 327 opening in fourth layer

[0101] 328 opening in fi fth layer

[0102] 33 adhesive

[0103] 4 radiation-emitting element

[0104] 41 radiation exit surface

[0105] 5 measurement unit

[0106] 51 measurement region

[0107] 52 reference region

[0108] 53 transparent plate

[0109] 54 measurement stack

[0110] 541 first measurement layer

[0111] 542 second measurement layer

[0112] 55 protective layer

[0113] 56 gas-impermeable layer

[0114] 57 cover layer

[0115] 6 detector unit 61 first photodiode

[0116] 62 second photodiode

[0117] 63 integrated circuit

[0118] 7 volume 8 structure

[0119] 9 gas

[0120] 10 electromagnetic radiation

Claims

Claims1. An optoelectronic device (1) for detecting a gas (9) comprising- a radiation-emitting element (4) configured for emitting an electromagnetic radiation (10) ,- a measurement unit (5) comprising a measurement region (51) and a reference region (52) , and- a detector unit (6) comprising at least a first photodetector region (61) and a second photodetector region (62) , wherein the measurement region (51) is arranged in a first beam path of the electromagnetic radiation (10) between the radiation-emitting element (4) and the first photodetector region ( 61 ) , wherein the reference region (52) is arranged in a second beam path of the electromagnetic radiation (10) between the radiation-emitting element (4) and the second photodetector region ( 62 ) , wherein the first beam path and the second beam path are reflective, wherein the optoelectronic device (1) is surface mountable, and wherein the measurement region (51) is configured for interacting with the gas (9) .

2. The optoelectronic device (1) according to the preceding claim, further comprising a substrate (2) , wherein electrical connection pads (21) of the optoelectronic device (1) are exclusively arranged on a side of the substrate (2) facing away from the radiation-emitting element (4) , the measurement unit (5) , and the detector unit (6) .

3. The optoelectronic device (1) according to at least one of the preceding claims, wherein the gas (9) is hydrogen.

4. The optoelectronic device (1) according to at least one of the preceding claims, further comprising a housing (3) , wherein the substrate (2) and the housing (3) surround a volume ( 7 ) , wherein the radiation-emitting element (4) , the measurement unit (5) , and detector unit (6) are arranged in the volume (7) .

5. The optoelectronic device (1) according to at least one of the preceding claims, wherein the housing (3) comprises a gas inlet (31) , wherein the gas inlet (31) is covered with a covering (32) impermeable to the electromagnetic radiation (10) emitted by the radiation-emitting element (4) .

6. The optoelectronic device (1) according to the preceding claim, wherein the covering (32) comprises a meander perforated plate, an inverse opal layer, a foamed plastic layer, or at least three layers of a perforated sheet metal.

7. The optoelectronic device (1) according to at least one of the preceding claims, wherein the detector unit (6) further comprises an integrated circuit ( 63 ) .

8. The optoelectronic device (1) according to the preceding claim, wherein the first photodetector region (61) and the second photodetector region (62) are arranged separately from the integrated circuit (63) .

9. The optoelectronic device (1) according to at least one of the preceding claims, wherein the measurement region (51) and / or the reference region (52) comprises a transparent plate (53) , a measurement stack (54) , and a protective layer (55) , wherein the measurement stack (54) is arranged between the transparent plate (53) and the protective layer (55) .

10. The optoelectronic device (1) according to the preceding claim, wherein the reference region (52) further comprises a gas- impermeable layer (56) , wherein the gas-impermeable layer (56) is arranged between the measurement stack (54) and the protective layer (55) .

11. The optoelectronic device (1) according to at least one of the claims 9 or 10, wherein the measurement region (51) and / or the reference region (52) further comprises a cover layer (57) , wherein the cover layer (57) is arranged on a side of the protective layer (55) facing away from the measurement stack (54) .

12. The optoelectronic device (1) according to at least one of the claims 9 to 11, wherein the transparent plate (53) is arranged on a side of the measurement region (51) and / or the reference region (52)facing the radiation-emitting element (4) and the detector unit ( 6 ) .

13. The optoelectronic device (1) according to at least one of the claims 11 or 12, wherein the measurement region (51) and / or the reference region (52) are arranged in the gas inlet (31) of the housing ( 3 ) , and wherein the cover layer (57) forms the covering (32) .

14. The optoelectronic device (1) according to at least one of the preceding claims, wherein the measurement region (51) and the reference region (52) are arranged directly adjacent to one another.

15. The optoelectronic device (1) according to at least one of the preceding claims, wherein the measurement region (51) and the reference region (52) are arranged on different sides of the radiationemitting element (4) .

16. The optoelectronic device (1) according to at least one of the preceding claims, further comprising at least one structure (8) for optically separating the radiation-emitting element (4) and the detector unit (6) at least partially.

17. The optoelectronic device (1) according to at least one of the preceding claims, wherein the detector unit (6) is mounted on the substrate (2) .

18. The optoelectronic device (1) according to at least one of the preceding claims, wherein the radiation-emitting element (4) is mounted on the substrate (2) or the detector unit (6) .

19. The optoelectronic device (1) according to at least one of the preceding claims, wherein the measurement unit (5) is spaced apart from the radiation-emitting element (4) and the detector unit (6) .

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