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Photo tour: what are they doing in the laboratory of hybrid nanophotonics and optoelectronics of the New Physics Institute ITMO

While everyone is at home, it's time to talk about the projects and technologies that are being worked on in our walls, and also to discuss equipment: glove boxes, vacuum chambers and reagents.

Attention: under a cat there are a lot of photos.

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What do the lab do


The laboratory of hybrid nanophotonics and optoelectronics has existed for three years at the ITMO Engineering Center . It develops products based on hybrid perovskites . This is a material with high light absorption in the visible range. For example, silicon hundreds of microns thick absorbs as much radiation as perovskite one micron. Due to the unique physical properties, it has found application in the production of light-emitting electrochemical cells (light-emitting electrochemical cells, LEC ), solar cells and nanolasers .

Still on the basis of the laboratory, students are taught. Basically, bachelors and masters of the ITMO Physical Engineering Physics go here, but there are students from other faculties and even universities - the SCAMT Institute, the Academic and Electrotechnical Universities. Junior students are engaged in project activities. They gain experience in a team and motivation for self-education.

Undergraduates conduct research in the framework of the preparation of qualification work. The most talented children get the opportunity to continue their studies as graduate students of the Faculty of Physics and Technology. One of the supervisors is Anvar Zakhidovwho has a laboratory in Dallas. It produces carbon nanotubes, another promising material. With its help, it is possible to produce transparent LEDs with good brightness characteristics or cascading LEDs. They emitters are located under each other, and not side by side. This approach reduces the size of displays.

Apparatus and equipment


The main tool in the laboratory is glove boxes. These are airtight containers for working with substances and reagents in a controlled environment. In the photo below - MBraun installation, the chamber of which is filled with pure nitrogen. This is an inert gas, so it does not interact with perovskite, and also displaces oxygen and water vapor from the chamber. A similar effect can be achieved using argon, but it is more expensive and more difficult to get in St. Petersburg.



Working with boxes requires certain skills. It is necessary to ensure that the samples are correctly introduced into the chamber, otherwise there is a risk that the nitrogen resource of the device is simply wasted. Therefore, each new employee undergoes a training course.





One of the glove boxes is reserved for working with perovskite solutions. These are perovskites diluted with salts and solvents of DMSO (dimethyl sulfoxide ) and DMF ( dimethylformamide ). They are stored in small test tubes.


Perovskite solution


Test tubes are signed and stored in plastic containers.

Thin perovskite films are obtained from the solution. The substance is sprayed on a special glass, which is mounted in a centrifuge cartridge and untwisted. At some point, an anti-solvent is added thereto. As a result, the material precipitates, forming a film.



Different perovskites have unique properties. Therefore, laboratory specialists are constantly practicing the technology of their application.



Finished films must be stored in an inert box. But for their short-term movement during research, it is permissible to use ordinary Petri dishes.



Also, the laboratory of hybrid nanophotonics and optoelectronics is engaged in the synthesis of perovskites. For this, there are all the necessary reagents and salts.



By changing the volumes of salts in the solution, it is possible to “move” the forbidden zone of perovskite from 1.5 eV to 3 eV. This feature allows you to collect cascading solar cells that absorb light with different wavelengths. It is enough to make several perovskites with various properties and make up a multilayer device from them.



In one of the glove boxes there is a thermal spraying chamber for the production of diode products. It is under vacuum, since purity is a very important parameter when working with nanophotonics. The chamber itself is a sealed vessel with four controlled stoves - crucibles, where the sprayed substance is loaded. Two crucibles are for metals, two for metal-organic compounds.

During operation, the chamber is pumped to an average vacuum — about 2.10 -6 atmospheres — and the crucible is heated to the evaporation temperature of the loaded material. Then these pairs rush up, where they are deposited through the mask onto the sample (perovskite film).



The mask allows you to choose almost any design of the sprayed film. These can be metal electrodes for connecting the device, as well as barrier carbon layers so that neighboring layers do not interact with each other. The masks themselves are attached to the stencil frame with screws. At one time, the camera can spray four modules with a size of 25x25 mm (in the figure below, these are yellow marks ).


Sample disk

In the production of an LED (or solar cell), the bottom contact is made from commercial ITO ( indium tin oxide) - translucent material. Using the method of photolithography, four strips of 3 mm each are etched in it. Glove boxes are applied with transport, active and barrier layers on top, and then metal contacts - electrodes are sprayed. The electrodes are also four strips of 3 mm, but perpendicular to the contacts of ITO. Thus, pixels of perovskite devices appear at the intersection - a total of sixteen pieces of 3x3 mm in size on each module.



Another pressurized laboratory box is used to characterize perovskite devices. Measuring equipment is installed inside: two solar simulators, a compact spectrometer and a spectroradiometer. The latter is a camera for assessing the illumination of LEDs - cd / m2, lux.

An integrating sphere was also established there. She does everything the same as the spraktroradiometer, only a little more accurately, since she "collects" the diode light from all sides.


Keithley 2400 Source Meter The Keithley 2400

source meter is also at the disposal of laboratory specialists. It allows you to measure the current-voltage characteristics of thin-film devices. The photo below shows a demo sample - an LED with a sprayed top electrode.





In one of the chambers there is a system for express-determination of film operability. Inside there is a syringe with In-Ga eutectic and a crocodile". Eutectic allows you to directly connect to perovskite so as not to “dust” the contacts in the thermal chamber. "Crocodile" plays the role of a pressure contact to pass current through the LED and light it. Thus, the electroluminescence spectrum can be measured.

The devices are very small, and you have to work with rubber gloves. To tighten a nut in them is already a big deal. Therefore, there are wrenches and tweezers in the cells.



The express test chamber also has a profilometer - it’s just a “finger” that rides on the surface and looks at its profile. With its help determine the film thickness, roughness, morphology.



Another device is an optical microscope. This is one of the main instruments because a fiber spectrometer is connected to it. The system allows you to locally record the spectrum of photoluminescence, transmission, reflection from the film. When students grow nanoparticles, they can study the glow characteristics of one of them. This is important because, depending on the particle size, the photoluminescence wavelength shifts and other characteristics change.

Other laboratory facilities


A chemical room is hidden behind one of the laboratory doors.



Located on its territory is allowed exclusively in overalls. Everything is strict with this - violators are removed from projects.



In addition to the chemical room, the laboratory has its own open space. This room is a converted ballroom.



Recent Modifications


The technological base of the laboratory of hybrid nanophotonics and optoelectronics is regularly improved. A crucible furnace was purchased last year. It is used to produce transport layers in highly efficient perovskite-based solar cells. High temperatures help to heat-treat glass substrates, accelerate the diffusion of metal contacts into the structure of transport layers of perovskite solar cells, and work with inorganic quantum dots.

A reaction block was also purchased for the synthesis of inorganic nanoparticles and the formation of active layers in perovskite LEDs, nano- and microlasers.

The laboratory recently acquired a system for studying the generation of optical harmonics of coherent radiation. It makes it possible to study nonlinear optical properties based on organo-inorganic compounds with integrated nanophotonic structures.

A precision immitance meter (LRC meter) has also appeared, which allows obtaining frequency characteristics of the impedance of perovskite films, as well as LEDs and solar panels based on them. Thanks to him, it is possible not only to characterize the material of the photoactive layer, but also to draw conclusions about the quality of the contacts of the devices when practicing the technology of their deposition.


On the left is a system for studying the generation of optical harmonics of coherent radiation. Right: hybrid nanophotonics and optoelectronics laboratory in January 2019


On the left is a precision immitance meter (LRC meter). To the right is a crucible furnace.

In addition to equipment, new research directions appeared. One of them is associated with the synthesis of perovskite crystals of a given shape and size. They make it possible to register interesting nonlinear effects and obtain functional nanomaterials. So, in 2019, engineers developed the smallest optically pumped dielectric laser. The resonator in the laser was a cubic perovskite crystal. Its size correlated with the long won radiation of the material.

Another actively developing area in the laboratory is the development of "bifunctional" devices. These are thin films of perovskite, which, depending on the applied voltage, can work both in the solar battery mode and in the LED mode. Prototypes and first patents have already been received. In the future, such films will find application in the implementation of smart windows - when a double-glazed window charges the battery in the afternoon, and in the evening works as an extended light source.


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