Polished Front Research Articles

A scalable method for fabricating monolithic perovskite/silicon tandem solar cells based on low-cost industrial silicon bottom cells

Tandem solar cells composed of perovskite and silicon (PVSK/Si TSCs) exhibit significant potential for improving the power conversion efficiency (PCE) and reducing the levelized cost of electricity. Currently, most tandem cells demonstrating high efficiencies utilize costly float zone (FZ) silicon wafers, which pose limitations for large-scale production due to their high expense. This study presents a scalable approach for manufacturing perovskite/silicon tandem solar cells using industrial silicon bottom cells. We employ a double-layer intrinsic amorphous silicon passivation layer to enhance the carrier lifetime of the bottom silicon cell. Additionally, we introduce a novel indium oxide doped with transition metals (IMO) transparent electrode to enhance near-infrared (NIR) light absorption. To achieve silicon bottom cells with a polished front surface, we utilize a cost-effective and time-saving saw damage etching process. The perovskite absorber is then deposited on the polished surface using slot-die coating. Furthermore, we coat the perovskite absorber with a mixed solution of FAI and mF-PEAI via slot-die coating to eliminate excess PbI2 on the surface and passivate surface defects. Through the integration of top and bottom sub-cells, we obtained a PCE exceeding 24.22 % from a 5 cm × 5 cm TSCs device (with an aperture area of 3.8 cm × 3.8 cm) and a PCE of 28.68 % from a 2.5 cm × 2.5 cm TSCs device (with an aperture area of 1 cm × 1 cm).

Zadania i rozwój wojsk operacyjnych Sił Zbrojnych Polskiej Rzeczypospolitej Ludowej w pierwszych 15 latach funkcjonowania Układu Warszawskiego

The article describes the organizational changes and modernization of the operational troops of the Armed Forces of the Polish People's Republic in the first 15 years of the existence of the Warsaw Pact. In the structure of the Polish Army, the aforementioned troops constituted the most important component intended for military operations at the operational level as part of the United Armed Forces of the Warsaw Pact. During the war, the operational troops were to create a higher operational union (the Polish Front), which was to include three Land Force Armies, the Air Force Army and operational forces of the Navy. The units of the first throw were constantly in combat readiness, thanks to which they could start combat operations almost immediately, in accordance with the operational plans of the Warsaw Pact Command. The changing and growing requirements of the battlefield forced the command of the Polish Army to modernize the structure and equipment of opera-tional troops. These issues are described based on literature and archival documents.

Problems of the Polish-Soviet war of 1919–1920 and the Riga Treaty in reflection of the RCP(b) Central Committee Politburo minutes of meetings

The role of the problems of the Polish-Soviet war and the Riga Treaty in the activities of the Politburo of the RCP(b) Central Committee is revealed. It is established that in 1919 this problem occupied an insignificant place in the work of the Politburo, the Polish-Soviet confrontation was given a secondary role against the background of the struggle of the Bolsheviks with the White Movement. The protocols of the Politburo of 1920 reflect the growing importance of the Polish front for Soviet Russia. But even in these circumstances, the issues of the Polish-Soviet war did not become dominant in the activities of the Politburo. It paid the greatest attention to the issues of propaganda work and the preparation and progress of peace negotiations with Poland in the summer and autumn of 1920. The materials of the Politburo meetings confirm that it was this party body that made decisions on key issues of Polish-Soviet relations, which were then implemented by Soviet diplomacy. The Belarusian question during the Polish-Soviet war was considered by the Politburo very rarely and only in the context of Soviet Russia’s achievement of its foreign policy goals.

18-та ДИВІЗІЯ ПІХОТИ У ТРАВНЕВОМУ НАСТУПІ 1920 РОКУ 6-ї АРМІЇ ВІЙСЬКА ПОЛЬСЬКОГО В УКРАЇНІ

The article concerns the 18 Iron Infantry Division (ID) of the Polish Army, which was one of the best divisions during the Polish-Soviet war of 1919-1921. In April 1920, the 18th Infantry Division took part in the Polish – Soviet War. After the first battles against the Russians in Podolia, the 18th ID participated in the Polish offensive in the Ukraine. It led to the capture of Kiev. From 26th May 1920, the 18th ID took part in the defensive battles of the 6th Polish Army in the area of Haisyn. On June 5th 1920, the Polish front in the Ukraine collapsed. It was a result of an offensive action of the 1st Cavalry Army of Semyon Budyonny. On June 29th 1920, one of the most glorious chapters in the history of the 18th Infantry Division began. It was a successful fight against Semyon Budyonny’s 1st Cavalry Army, in the region of Ostroh, Dubno and Brody in Volhynia. The Battle of Brody for some time stopped the Red Army's offensive on the southern section of the front.During those battles, the soldiers of General Krajowski gained great experience and reputation of the war. Then the 18th ID was transported near Warsaw. The 18th ID formed part of Wladyslaw Sikorski’s 5th Army. It participated in the Battle of Warsaw, which became the turning point of the 1920 War. After the battle, the 18th ID also took part in the winning battles for the Polish side in Volhynia and Polesie, where it ended the war in 1920.The article reproduces and characterizes in detail the participation of the 18th Infantry Division, being part of the 6th Army of the Polish Army, in battles with Soviet troops between April 25 and May 25, 1920. During the march to the east of the 18th DP under the command of General Franciszek Kralicek-Krajowski, fighting side by side with the Ukrainian troops against the Red Army, she captured many places, taking numerous Russian prisoners and capturing many spoils, including rolling stock, weapons, ammunition and food. After stabilizing the front, 18th Infantry Division took a position on the Sob River near Hajsyn.

Prosody-segment Interactions in the Acoustics of Polish Front Vowels

This paper presents an acoustic study devised to investigate the effects of three presumably distinct prosodic position on the phonetic realisation of Polish front vowels in #CV (that is, following a prosodic boundary and a consonantal onset) and #VC sequences (that is, immediately following a prosodic boundary). The results of the experiment suggest that Polish does not seem to distinguish between utterance-initial and phrase-initial positions, with some contrasts present between these two positions and phrase-medial tokens with respect to F1. No effects of position have been found for F2 or vowel duration. There are also no clear differences on the acoustic realisation of vowels depending on whether or not they are adjacent to the prosodic boundary. These results raise questions about the nature of prosodic structure in Polish as compared to other languages which show more robust effects.

Донские казаки на польском фронте в 1919 году

Донские казаки на польском фронте в 1919 году

The Third World War as Envisaged by Polish Generals at the Turn of the 1950s and the 1960s

This article gives an account of the military exercises code-named ‘Tempest’ and carried out in the autumn of 1961 by the army of the Polish People’s Republic under the supervision of Soviet officers. In the course of the war game the Polish staff members were placed in charge of the Baltic Front which, was given the task of seizing control of Denmark and the northern parts of Holland and Germany. These were the first large scale military exercises (a separate Polish front) to be organized after 1956.

Three-dimensional ultrasound images of Polish high front vowels

The 3-D ultrasound method has been applied to collect data on Polish high front vowels. In particular, Polish has one unambiguous high front vowel and another one that in the phonological literature is variously referred to as high central or back unrounded and transcribed as [ɨ]. While there exists a sizeable body of articulatory research on Polish, including X-rays from as early as the 50s and 60s, the ultrasound data reveal more detail about the position of the tongue center and tongue root. The data evaluated so far support the view that the vowel transcribed as [ɨ] is a front vowel. The two front vowels differ in the position of the tongue root, relative raising of the tongue, and extent of lip gesture, but do not differ substantially with regard to tongue body advancement on the font-back axis. The data also capture the temporal aspect of speech, and together with time-aligned audio recordings and video recordings of the lips, allow for fine-grained analysis of the acoustic effects of these articulatory gestures.

Novel detectors for traceable THz power measurements

Several novel types of detectors for the measurement of electromagnetic radiation in the THz spectral range are described. Firstly, detectors based on pyroelectric foil coated with different absorbers have been developed focusing on the following features: high accuracy due to well-characterized absorption, high sensitivity, large area absorbers and frequency and polarization independence. A three-dimensional design with five absorptions gave an overall absorption of more than 98 %. Secondly, detectors based on pyroelectric foils with thin metal layers were realized. An absorption of 50 % can be obtained if the thickness of the layers is carefully adjusted. According to electromagnetic theory this degree of absorption is independent of the polarization and frequency of the radiation in a wide range from at least 20 GHz to 5 THz. The third type of detector is based on a new type of volume absorber with a polished front surface and a gold-coated back side. It is the absorber of choice of the standard power detector for disseminating the spectral power responsivity scale. This standard detector allows the application of a physical model to calculate its spectral responsivity in the range from 1 THz to 5 THz if the detector has been calibrated at one single frequency. Finally, a THz detector calibration facility was set up and is now in operation at PTB to calibrate detectors from customers with an uncertainty as low as 1.7 %.

Mrs. Professor

Mrs. Professor

Surface-Texturing of Single-Crystalline Silicon Wafers

In this work, alkaline-based anisotropic etchants, tetramethylammonium hydroxide (TMAH) and potassium hydroxide (KOH)/isopropyl alcohol (IPA) solutions, have been used for the surface texturing of the single-crystalline silicon wafers used for solar cells. The pyramid morphology produced by the surface texturing can reduce the surface reflection of the incident light and increase the light absorption so that the efficiency of the solar cells can be increased. The experimental data shows that the optimized surface texturing has been obtained with 5 wt. % TMAH anisotropic etching at 80 °C. The surface reflectance of the polished front surface can be reduced to 17 % and the surface reflectance of the unpolished backside surface can be reduced to 3 %, respectively. This result shows that the anisotropic etching can effectively reduce the surface reflectance. While for the surface texturing with KOH/IPA mixture, the front surface reflectance can only be reduced to 35 % and the backside surface reflectance can only be reduced to 5 %, respectively. Besides, debris of Si nano-crystals exists around the pyramid base area when texturing with the KOH/IPA mixture.

Light trapping effect of patterned back surface reflectors in substrate-type single and tandem junction thin-film silicon solar cells

Light trapping is a key issue to boost the efficiency of thin-film Si solar cells including μc-Si:H. In this paper, effect of textured back reflectors on light trapping in μc-Si:H cells has been investigated with self-orderly patterned Al substrates obtained by anodic oxidation. With increase in the period of the patterned substrates from 0 to 1.1 μm, the short circuit current densities of 1-μm-thick μc-Si:H cells on the patterned substrates significantly increase from 18 to over 24 mA/cm 2, which is attributed to the improved light trapping in the infrared region. It has been clarified that this enhanced light-trapping effect in longer wavelengths is mainly attributed to the improved light scattering at the rear side by comparing μc-Si:H solar cells with polished and as-deposited front surfaces. The effectiveness of the patterned Al substrates has also been demonstrated in an a-Si:H/μc-Si:H tandem cell with a bottom cell thickness of 1 μm, showing a higher conversion efficiency than the reference cell.

An Investigation into Fracture of Multi-Crystalline Silicon

As the thickness of multi-crystalline silicon solar cells continues to reduce, understanding the mechanical properties of the material is of increasing importance. In this study, a variety of techniques are used to study multi-crystalline silicon. Fracture tests are performed using four- and three-point bending. The fracture stress of as-sawn material reduces with increasing beam width and is increased in beams with a polished front surface. This indicates that fracture initiates from surface flaws. Modifications to standard fracture testing, including testing under liquid, are made so that beams fracture into just two pieces. By determining the crystallography either side of the location of fracture, multi-crystalline silicon was found to fail by transgranular fracture in the samples studied. Further evidence for this is gained from indentation experiments at grain boundaries. In order to understand the relative strength of grain boundaries, new approaches need to be considered. Therefore, a novel micromechanical technique, which enables individual grain boundaries to be studied, has started to be applied to multi-crystalline silicon. A focused ion beam is used to mill micron-scale cantilevers across notched grain boundaries, which are then loaded to fracture using the tip of a nanoindenter. The technique is shown to reproduce the known fracture toughness of {110} planes in single-crystal silicon, giving a value of 0.7 ± 0.3MPam1/2. Preliminary results are presented for fracture of multi-crystalline silicon.

First known lenses originating in Egypt about 4600 years ago.

The first lenses (ca. Vth Dynasties of the Old Kingdom of Egypt. These lenses are found in The Louvre Museum in Paris and the Egyptian Museum in Cairo. They were components of extraordinary eye constructs in statues which had unique qualities. Namely, the "eyes" appear to follow the viewer as he/she rotates about these statues in any direction. This effect can be photographed and reproduced 2620-2400 B.C., 4620-4400 Before Present=B.P.) appeared mainly during the IVth and optically. This effect has been modeled here. The lenses were ground from high quality (!) rock crystal (a form of quartz, n approximately 1.46). Each had a convex and highly polished front "corneal" surface. Thus, in a sense, these were multifocal lenses. The iris aperture may or may not have been open to a substantial posterior "vitreous" cavity formed largely by curved copper plates which extended forward to create the lid structures of these eyes. Were these a form of schematic eyes? Could such fine quality and complex (sophisticated) lenses be the first lenses? Clearly, the observer was intended to look at these eyes and follow their apparent movements. The total structure of these eyes indicated an advanced understanding of ocular anatomy and a surprising knowledge of optics. There are many questions.

Infrared laser interferometric thermometry: Extension to batch processing environments

Infrared laser interferometric thermometry (IRLIT) is a noncontact technique for measuring the temperature of single semiconductor substrates (with polished front and back surfaces) from thermally induced changes in wafer thickness and refractive index. It is suggested that IRLIT can be extended to a batch processing environment by making use of antireflection coatings for all but the wafer(s) of interest. This concept is tested with an IRLIT measurement of the temperature of a bare Si wafer sandwiched between several AR-coated Si wafers stacked on a hotplate. The data for this generic wafer arrangement confirm the applicability of IRLIT to situations such as temperature measurement of selected-position wafers in fully loaded boats during heating or cooling in a tube furnace.

Wavelength-modulated interferometric thermometry for improved substrate temperature measurement

Interferometric thermometry is a promising noncontact technique for measuring the temperature of transparent substrates (with polished front and back surfaces) from thermally induced changes in sample thickness and refractive index. However, for substrates of uniform thickness, the technique is not sensitive to the direction of temperature change, thus restricting its use to situations in which the temperature variation is monotonic. In this paper, we present some new schemes for interferometric thermometry based on the wavelength modulation capabilities of the distributed feedback laser diode. These schemes allow both the magnitude and direction of temperature change to be determined. One scheme utilized to measure temperature changes in a silicon wafer during thermal cycling is described in detail. In addition, the calibration factors required to convert the thermally induced reflectance oscillations (‘‘fringes’’) of known-thickness samples into temperature change are provided for Si and GaAs at wavelengths near 1.5 μm.

Fretting fatigue of continuous carbon fibre reinforced polymer composites

Continuous carbon fibre reinforced epoxy resin laminates were exposed to a fatigue loading. Simultaneously, cylindrical metallic pins with flat and polished front surfaces were pressed against the specimen surfaces with an apparent contact pressure between 10 and 23 MPa. The peak-to-peak oscillation width in the contact region amounted to about 700 μm. Fatigue life of the composite could drastically be reduced by this additional fretting component, if load bearing 0° layers were damaged by fretting. This paper studies the mechanisms of damage development in carbon fibre reinforced laminates under fretting fatigue conditions and proposes a quantitative measure for the degree of fretting fatigue damage. The influence of the loading conditions (contact load, counterpart material and slip amplitude) is investigated.

Identification of defects induced by heavy metal contamination on Si(100) surface using TEM

It is well known that heavy metallic contaminations are harmful to the performance of silicon devices. There are several investigations about the precipitation behaviors of heavy metals on Si wafers. In this study, the observations of transmission electron microscopy (TEM) were carried out to identify defects induced by intentional Cu, Ni and Fe contamination on Si(100) surface.P-doped 5-12 Ω·cm, 5inch-diameter CZ-Si(100)wafers, with a mirror polished front surface and only chemically etched back surface, were used. The front surfaces of wafers were contaminated quantitatively by the technique proposed previously. The concentrations of each element on the surface were determined with an atomic absorption spectrophotometer. Cross-sectinal and plane TEM observations were conducted with a Hitachi H-9000 at 300KV. The conditions of annealings are shown in Fig.1.When the wafer was contaminated with Cu, colony precipitates were observed within a thin region near an interface of Si and SiO2 formed during the annealing. Each precititate was the same crystallographic orientaion and lies along Si(110) plane(Fig.2).

金属表面反射型Ｃａｕｓｔｉｃｓ法による工具内応力の測定に関する基礎研究

In this paper the fundamental investigations are performed to measure the stresses at the cutting edge during metal cutting operation by using of the method of Caustics formed by reflected light ray from the metal surface. In standard method of Caustics the models made of the transparent material are used, but for the stress analysis in the cutting tool under the actual operating conditions it is needed to investigate the difference from using the transparent model by performing the experiments using the metallic model. Two dimensional problems are treated and the objects of study are half plane and wedge shaped plane loaded perpendicularly or obliquely. Specimens are made of aluminium plate of about 6 mm thickness. The Caustics patterns formed by the reflected light from the polished front surface were observed and those characteristics with the loading conditions are investigated in detail. On the other hand the computational patterns based on the optical theory are plotted. These two patterns are coincided accurately enough. Furthermore it was found that the presented results for the metallic specimens were similar to those of previous report for the transparent specimens under the same loading conditions.

The Championship of the Universal Class Struggle

The Championship of the Universal Class Struggle, a circus scenario, was written in the Fall of 1920 during Mayakovsky's work at Window ROSTA. It is possible to establish almost the exact date from the text. The line stating that Pilsudski, the Polish Champion, “doesn't want to fight anymore” refers to the armistice at the Polish front concluded on Oct 20, 1920. In the last lines, the Referee urges spectators to join the Red Army in the fight against Wrangel; the Red Army defeated Wrangel on Nov. 15, 1920. Thus, “The Championship” must have been written between Oct. 20 and Nov. 15, 1920.The propaganda themes and characters from “Championship” are also present in other works written by Mayakovsky in the Fall of 1920. The title, The Championship of the Universal Class Struggle, is a line in the poem “150,000,000” written in 1919-20.