Strain may enable better perovskite solar cells

Researchers from the University of California San Diego, King Abdullah University of Science and Technology and the Air Force Research Laboratory have developed a technique that could enable the fabrication of longer-lasting and more efficient perovskite solar cells, photodetectors, and LEDs.

Strain-engineered, single crystal thin film of perovskite imageStrain-engineered, single crystal thin film of perovskite grown on a series of substrates with varying compositions and lattice sizes. Image Credit: David Baillot/UC San Diego Jacobs School of Engineering.

A major obstacle is the tendency of one of the best-performing perovskite crystals, α-formamidinium lead iodide (HC(NH2)2PbI3, known as α-FAPbI3), to assume a hexagonal structure at room temperature, in which photovoltaic devices are required to operate. This hexagonal structure cannot respond to most of the frequencies of light in solar radiation, and is hence not useful for solar applications as it could be. The team therefore set out to stabilize the structure of α-FAPbI3, using a simple but useful approach known as strain engineering, which has been used to tune the electronic properties of semiconductors.

MIT team uses pervovskite PV to power “internet of things” sensors

MIT researchers have designed perovskite photovoltaic-powered sensors that could potentially transmit data for years before they need to be replaced. To this end, the team mounted thin-film perovskite cells as energy-harvesters on inexpensive radio-frequency identification (RFID) tags.

MIT team design PSC-powered sensors on RFID tags that work in sunlight and dimmer indoor lighting image

The cells could power the sensors in both bright sunlight and dimmer indoor conditions. Moreover, the team found the solar power actually gives the sensors a major power boost that enables greater data-transmission distances and the ability to integrate multiple sensors onto a single RFID tag.

Researchers find environmental impacts on organometal halide perovskites

Researchers from the University of Tennessee and Oak Ridge National Laboratory have found that the environment is a non-trivial component in the operation of organometal halide perovskite (OMHP) devices, playing an important role in the charge transport behavior at the electrode/crystal interface of OMHPs due to coupling between surface mediated redox processes and bulk ionic species.

Environment factors impact transport and stability in OMHPs and but offer new opportunities in sensing and energy storage image

The team explored environmental and interface effects, namely transport behavior and origins of the gas sensitivity, in MAPbBr3 single crystal (SC) devices using impedance spectroscopy and G-Mode Kelvin Probe Force Microscopy (G-KPFM). Strong resistive response was found to occur when the crystals were exposed to different environments. It was shown, among other things, that SC response to the environment is extremely different at the surface as compared to the bulk due to the disorder surface chemistry.

Researchers design an ecofriendly and low-cost method for fabricating high performance perovskite photodetectors

Perovskites have shown potential for use as high performance photodetectors, where the responsivity and detectivity of the perovskite photodetector (PePDs) can be improved by engineering its interfacial properties. Researchers from the University of Electronic Science and Technology of China (UESTC) and City University of Hong Kong have reported the applications of bio-inspired materials, deoxyribonucleic acid (DNA) and guanine, as functional interfacial layers for high performance PePDs.

The schematic diagram of the PePD image

The best bio-material modified PePDs exhibit a ∼2× enhancement of the photo-current than that of the reference PePDs with no modifications. Further optimization of the thickness for the bio-materials based functional layers enables the PePD to achieve a remarkable responsivity of 0.37 A W−1 and detectivity of 1.85 × 1012 Jones at the wavelength of 745 nm.

Perovskites may help improve detectors for nuclear security

Researchers from the University of Florida and Pacific Northwest National Laboratory set out to improve global nuclear security by enhancing radiation detectors, and discovered, after evaluating a diverse list of over 60 candidates for alternative semiconductor compounds, that a hybrid organic-inorganic perovskite has the highest potential to succeed.

Perovskite sensors can improve equipment used for detecting and identifying radioactive materials imageBetter sensors can improve equipment used for detecting and identifying radioactive materials. (Image credit: Pacific Northwest National Laboratory)

The scientists reported that the identification of better sensor materials and the development of smarter algorithms to process detector signals are essential to enhance radiation detectors. Paul Johns, Physicist, University of Florida, said: "The end users of radiation detectors don’t necessarily have a background in physics that allows them to make decisions based on the signals that come in. The algorithms used to energy-stabilize and identify radioactive isotopes from a gamma ray spectrum are therefore key to making detectors useful and reliable".