Transistors

The majority of monolithic perovskite/Si tandem solar cells (TSCs) have been built on heterojunction (HJT) Si solar cells, which have seen limited industrial uptake due to manufacturing cost and concern over the viability of metal electrodes and transparent conductive oxides (TCOs) incorporating expensive elements. Recently, researchers from The Australian National University, University of Melbourne and University of New South Wales demonstrated that high efficiencies of perovskite/Si TSCs can be achieved with Si bottom cells based on a double-side poly-Si/Si dioxide (SiO₂) passivating contact (poly-Si cell) without silver or transparent conductive oxides (TCOs), fabricated using mass-production techniques. 

In addition, a novel low-absorption, dopant-free bilayer-structured hole transport layer (HTL) composed of ultra-thin poly(N,N′-bis-4-butylphenyl-N,N′-bisphenyl)benzidine (Poly-TPD) and 2,2′,7,7′-tetra(N,N-di-p-tolyl)amino-9,9-spirobifluorene (Spiro-TTB) double layers was developed for the perovskite top cell, which passivates the perovskite surface and enhances the near-interface conductivity, thus increasing the open-circuit voltage and fill factor. 

As silicon-based transistors approach their limits, researchers are exploring alternative materials to continue progress in semiconductor technology. Carbon nanotubes (CNTs) are considered promising candidates for next-generation electronics due to their exceptional electrical properties and nanoscale dimensions. Yet, the challenge of precisely controlling the electronic characteristics of CNTs has hindered their widespread adoption in practical applications.

Researchers at China's Peking University, Zhejiang University and Chinese Academy of Science (CAS) have developed an inner doping method by filling CNTs with 1D halide perovskites to form a coaxial heterojunction, which enables a stable n-type field-effect transistor for constructing complementary metal–oxide–semiconductor electronics.

Researchers at the Chinese Academy of Sciences (CAS), in collaboration with Japan's Yamagata University, developed three isomeric bisphosphonate-anchored self-assembled molecules (SAMs) to achieve highly efficient and stable inverted perovskite solar cells (PSCs).

The wettability, absorbability and compactness of SAMs, which are used as hole-transporting layers (HTLs) for PSCs, critically affect the efficiency and stability of the devices. Therefore, the researchers proposed a molecular strategy to synthesize three bisphosphonate-anchored indolocarbazole (IDCz)-derived SAMs, namely IDCz-1, IDCz-2, and IDCz-3. The three SAMs with different positions of the two nitrogen atoms in the IDCz unit were each employed on conductive oxide substrates for inverted PSCs.

Researchers from Northwestern University, University of Toronto, ShanghaiTech University, University of Victoria and Arizona State University have developed highly stable, highly efficient 0.05cm² perovskite solar cell with a PCE of 26.15%, certified by a National Renewable Energy Laboratory-accredited facility. The team said that the prior certified world record published in a scientific journal was 25.73%.

A 1.04 cm² device had a certified power conversion efficiency of 24.74%, also a record for its size. The best devices retained 95% of their initial PCE following 1,200 hours of continuous solar illumination at a temperature of 65 degrees.

Researchers at the University of Potsdam, Humboldt-University of Berlin, University of Wuppertal, Swansea University, University of Oxford, East China University of Science and Technology, Friedrich-Alexander-University Erlangen-Nürnberg and HZB have shown that ion-induced field screening is a dominant factor in the operational stability of perovskite solar cells (PSCS). 

The rather poor perovskite stability is usually attributed to electronic defects, electrode oxidation, the ionic nature of the perovskite, or chemical decomposition under moisture and oxygen. Understanding the underlying degradation mechanism is crucial to enable targeted improvements. "In our article, we demonstrate that an increasing concentration of defects in the cells is apparently not a decisive factor for degradation," says Martin Stolterfoht, former leader of the Heisenberg junior research group PotsdamPero at the University of Potsdam and now professor at the Chinese University of Hong Kong.

Researchers at the University of Oxford, University of Toronto, Peking University, Kunming Medical University, Yunnan University, Chinese Academy of Sciences (CAS) and Academia Sinica have reported a chemically stable and multifunctional buffer layer material, ytterbium oxide (YbOx), for p-i-n perovskite solar cells (PSCs) by scalable thermal evaporation deposition. 

This YbOx buffer has been used in p-i-n PSCs based on narrow-bandgap perovskite light-absorbing layers, with certified power conversion efficiencies exceeding 25%.

Researchers at Graphenea, University of Utah and Kairos Sensors have examined a perovskite-based graphene field effect transistor (P-GFET) device for X-ray detection.

The device architecture consisted of a commercially available GFET-S20 chip, produced by Graphenea, with a layer of methylammonium lead iodide (MAPbI₃) perovskite spin coated onto the top of it. This device was exposed to the field of a molybdenum target X-ray tube with beam settings between 20 and 60 kVp (X-ray tube voltage) and 30–300 μA (X-ray tube current). Dose measurements were taken with an ion-chamber and thermo-luminescent dosimeters and used to determine the sensitivity of the device as a function of the X-ray tube voltage and current, as well as source-drain voltage.

Researchers from Pohang University of Science and Technology (POSTECH), Chinese Academy of Sciences (CAS) and University of Electronic Science and Technology of China have developed perovskite transistors through the use of three distinct perovskite cation processes. 

The team showed that pure-tin perovskite thin-film transistors can be created using triple A cations of caesium–formamidinium–phenethylammonium. This approach reportedly leads to high-quality cascaded tin perovskite channel films with low-defect, phase-pure perovskite/dielectric interfaces.

TCI has launched a range of molecular dopants that can significantly increase the charge carrier density and modify the energy levels in organic electronics devices. Molecular dopants offer a versatile platform to tune the optoelectrical and electrical properties of organic semiconductors to application-specific demands, allowing advantages like increasing the electrical conductivity and mobility by orders of magnitude and improving contact properties in various electronic and optoelectronic devices.

TCI's p-type and n-type dopants can be applied to various organic electronics devices, such as: carrier transport layers of organic light-emitting diodes (OLEDs), organic photovoltaics (OPVs), perovskite solar cells (PSCs), and perovskite quantum dot LEDs, as well as active layers of organic field-effect transistors (OFETs), OPVs, and thermoelectric devices in the field of organic electronics research.

An international research group that included teams from Vrije Universiteit Amsterdam, University of Fribourg, the University of the Basque Country and the University of New South Wales has assessed the levels of efficiency and stability that perovskite solar cells (PSCs) have to achieve in order to become an economically viable technology to compete with crystalline silicon cells in the rooftop segment.

The scientists assessed the necessary lifetime (LT) of a perovskite module, which they defined as the time until a module has 80% of its initial efficiency, as a function of efficiencies to be competitive in the levelized cost of electricity (LCOE). They found that perovskite solar modules might need to provide 20% efficiency for at least 36 years, or 25% efficiency for a minimum of 21 years, if they want to compete with conventional PV panels.