Transistors

Perovskite solar cells (PSCs) that incorporate a 2D/3D perovskite layer tend to demonstrate enhanced stability compared to that of their purely 3D counterparts, possibly thanks to the superior chemical stability of the 2D perovskite layer. However, the poor electrical properties of the 2D perovskite layer also limit further improvement of device performance. Moreover, the most effective hole transport layer (HTL) in 2D/3D PSCs, lithium bis(trifluoromethylsulfonyl)imide (Li-TFSI)-doped 2,2′,7,7′-tetrakis(N,N-di(4-methoxyphenyl)amino)-9,9-spirobifluorene (spiro-OMeTAD), usually needs prolonged exposure to air to improve its conductivity, which to some extent increases the risk of water/oxygen infiltrating into the perovskite layer, leading to the degradation of the perovskite active layer.

Researchers at China's Henan University and Chinese Academy of Sciences (CAS) have developed a multifunctional dopant, tin oxysulfide (SnSO) in the spiro-OMeTAD layer, to improve the efficiency and stability simultaneously.

Tokyo Chemical Industry (TCI), a global supplier of laboratory chemicals and specialty materials, is now offering Phenylethylamine Hydroiodides materials, used for surface treatment of perovskite layers in solar panels. These materials improve the stability of the solar panels.

Research has shown that by applying the Phenylethylamine Hydroiodides materials, one can expect improved stability of over 90%. In one research, the 1,2-Benzenediethanamine Dihydroiodide was applied to a perovskite PV device (FTO/TiO2/SnO2/perovskite/Amine Iodide/Spiro-OMeTAD/Au), and achieved an increase in stability of over 90% after 1,100 hours. See here for more info.

Researchers from China's National Center for Nanoscience and Technology, Chinese Academy of Sciences (CAS) and Beihang University have demonstrated a series of ultrastable Dion−Jacobson (DJ) perovskites for photovoltaic applications. They went on to develop a 2D Dion-Jacobson (DJ) perovskite solar cell that showed high stability while achieving a power conversion efficiency of 19.11%.

Schematic illustration of the blade-coating film and the corresponding device configuration under atmospheric environment at room temperature. Image credit: Nature Communications 

Two-dimensional (2D) Dion-Jacobson (DJ) phase perovskites have drawn attention from academia due to their stability against harsh environmental conditions and their competitive performance in optoelectronic applications. Solar cells based on DJ perovskites, however, have so far shown comparatively poor performance compared to their 3D counterparts.

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.