Researchers develop self-polarized RGB device based on micro-LEDs and perovskite-in-polymer films for backlight applications

Researchers from China's Xiamen University, Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province (IKKEM), Yang Ming Chiao Tung University and Hon Hai Research Institute have reported a self-polarizing RGB device utilizing semipolar micro-LEDs and perovskite-in-polymer films aimed at improving backlight applications.

Structure of an LCD based on semipolar blue μLEDs excite anisotropic perovskite NCs as backlight. Image from Opto-Electronic Advances

In backlighting systems for LCDs, conventional red, green, and blue (RGB) light sources that lack polarization properties can result in a significant optical loss of up to 50% when passing through a polarizer. To address this inefficiency and optimize energy utilization, the scientists developed a high-performance device designed for RGB polarized emissions. The device uses an array of semipolar blue µLEDs with inherent polarization capabilities, coupled with mechanically stretched films of green-emitting CsPbBr3 nanorods and red-emitting CsPbI3-Cs4PbI6 hybrid nanocrystals. 

Read the full story Posted: Apr 05,2024

Researchers design efficient perovskite-CIGS tandem solar cell on conductive steel substrate

Researchers at the University of Sydney, Microsolar, University of New South Wales and MiaSolé Hi-Tech Corp. have reported a monolithic perovskite–CIGS tandem solar cell on a flexible conductive steel substrate with an efficiency of 18.1%, the highest for a flexible perovskite–CIGS tandem to date, representing an important step toward flexible perovskite-based tandem photovoltaics.

The advantage of the flexible and conductive steel substrate is that the steel itself can act as both a substrate and an electrode for either large-area-monolithic-panel or smaller-area-singular single-junction or multi-junction cell fabrication.

Read the full story Posted: Apr 04,2024

Researchers use multifunctional hole transporting material to realize efficient and stable perovskite solar cells

Researchers at China's Tsinghua University, Zurich University of Applied Sciences and University of Ferrara have developed a perovskite solar cell with a new hole transport material that promises enhanced efficiency and stability while also ensuring a scalable fabrication technique.

The team explained that the new organic hole-transporting material, named T2, offers a performance advantage over conventional materials like spiro-OMeTAD as its characteristics, including unique electronic, structural, and chemical properties, synergistically enhance the efficiency of hole extraction and significantly reduce charge recombination at the interface with the perovskite layer.

Read the full story Posted: Apr 02,2024

Researchers find ion-induced field screening to be a dominant factor in the operational stability of perovskite solar cells

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.

Read the full story Posted: Mar 31,2024

Researchers develop new technique for flexible perovskite solar cells with improved efficiency

High power conversion efficiency (PCE) flexible perovskite solar cells (FPSCs) are highly desired power sources for applications like aerospace and flexible electronics. However, their PCEs still lag far behind their rigid counterparts. To address this issue, researchers from Tsinghua University and National Center for Nanoscience and Technology developed a new fabrication technique that increases the efficiency of FPSCs, paving the way for use of the technology on a much larger scale. The scientists reported a high PCE flexible perovskite solar cell by controllable growth of a SnO2 electron transport layer through constant pH chemical bath deposition (CBD). 

The team developed a new chemical bath deposition (CBD) method of depositing tin oxide (SnO2) on a flexible substrate without requiring a strong acid, which many flexible substrates are sensitive to. The new technique allowed the researchers more control over tin oxide growth on the flexible substrate. Tin oxide serves as an electron transport layer in the FPSC, which is critical for power conversion efficiency.

Read the full story Posted: Mar 28,2024

Researchers design perovskite solar cell with 31.31% efficiency using unique perovskite material

Researchers from Bangladesh, Saudi Arabia, Pakistan, USA, Nepal and China have explored the fascinating structural, optical, and electronic features of calcium nitrogen iodide (Ca3NI3) as an attractive material for developing absorbers for efficient and reasonably priced solar cells. 

Potential applications as an absorber layer in heterostructure solar cells for the perovskite material Ca3NI3 have been thoroughly studied theoretically. For the Ca3NI3 absorber-based cell structure with CdS as the ETL layer, the best PV values were discovered using the SCAPS-1D simulator. Working temperatures, interface densities of active materials, doping densities, and layer thicknesses were all carefully considered while analyzing the PV performance. 

Read the full story Posted: Mar 27,2024

Researchers develop "all-in-one" organic ligand for emitting perovskite nanocrystals

Perovskite nanocrystals (PNCs) have considerable potential as next-generation display materials thanks to their excellent photoluminescence quantum yield (PLQY), wide color gamut, and narrow emission bandwidth. However, due to their weak stability against solvents, their patterning remains a challenge. In a recent study, researchers at Ajou University, Hanyang University, Sungkyunkwan University, Macquarie University and Kongju National University developed functional organic ligands (AzL1-Th and AzL2-Th) for the fine pixelation of perovskite nanocrystal (PNC) displays. 

Functional ligands containing photocurable azide moieties exhibit good charge transport properties and fast and efficient photocrosslinking performance, while maintaining a high PLQY. The team successfully demonstrated the crosslinked PNC light emitting diodes using AzL1-Th. The results suggest the high potential of photocurable ligands for the micro-patterning of PNC films without film damages.

Read the full story Posted: Mar 25,2024

Researchers use DMAFo additive to make better perovskite solar cells

Researchers from the University of Science and Technology of China, Hefei National Research Center for Physical Sciences at the Microscale, Chinese Academy of Sciences and University of Colorado (CU Boulder) have reported an innovative method to manufacture perovskite solar cells. 

A major challenge in commercializing perovskite solar cells at a commercial scale is the process of coating the semiconductor onto the glass plates which are the building blocks of panels. Currently, the coating process has to take place in a small box filled with non-reactive gas, such as nitrogen, to prevent the perovskites from reacting with oxygen, which decreases their performance. “This is fine at the research stage. But when you start coating large pieces of glass, it gets harder and harder to do this in a nitrogen filled box,” said Michael McGehee, a professor in the Department of Chemical and Biological Engineering and fellow with CU Boulder’s Renewable & Sustainable Energy Institute. 

Read the full story Posted: Mar 22,2024

Researchers develop high-performance bifacial perovskite solar cells using single-walled carbon nanotubes

Researchers at the University of Surrey, University of Cambridge and Chinese Academy of Sciences, Xidian University, and Zhengzhou University have developed a novel approach for bifacial perovskite devices using single-walled carbon nanotubes as both front and back electrodes.

Single-walled carbon nanotubes offer high transparency, conductivity, and stability, enabling bifacial PSCs with a bifaciality factor of over 98% and a power generation density of over 36%. 

Read the full story Posted: Mar 19,2024

Researchers develop method to regulate the hole transport layer for efficient perovskite solar cells

Researchers at CAS (Chinese Academy of Sciences) and Henan University have developed a nanomaterial-regulated doping strategy to pre-oxidize spiro-OMeTAD into radicals in the precursor solution with tin sulfoxide (SnSO) nanomaterials prepared at high temperature. The team increased the photoelectric conversion efficiency (PCE) of perovskite solar cells (PSCs) to 24.5% using the inorganic SnSO as a dopant to oxidize and regulate the organic hole transport layer 2,2′,7,7′-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9-spirobifluorene (spiro-OMeTAD).

Spiro-OMeTAD is an important hole transport layer (HTL) material. To enhance the charge transport capability of spiro-OMeTAD, lithium trifluoromethanesulfonyl imide (Li-TFSI) is required to mediate the reaction between oxygen and spiro-OMeTAD. However, this traditional doping method has low doping efficiency, and excessive Li-TFSI will remain in the spiro-OMeTAD film, leading to a decrease in the compactness and long-term conductivity of the film. The duration of the oxidation reaction usually takes 10 to 24 hours to reach the desired conductivity and work function. In this study, the researchers developed a fast and reproducible strategy to control the oxidation of the nanomaterial. They used SnSO nanomaterial to pre-oxidize spiro-OMeTAD to spiro-OMeTAD+TFSI- free radicals in precursor solutions. This improved the conductivity, optimized the energy level position of HTL, and achieved a high PCE of 24.5%.

Read the full story Posted: Mar 18,2024