Research Highlight

Solution-processed AgCNT transparent electrode for Semi-transparent Organic Solar Cell

In the article at Advanced Optical Materials (DOI/10.1002/adom.202002108), the AgCNT film is employed as a top transparent electrode of semi-transparent organic solar cell (STOSC). STOSCs with solution-processed AgCNTs transparent electrode exhibit higher average visible transmittance and color rendering index than that with evaporated thin metal electrode, and comparable efficiency.

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Fully Inorganic CsSnI3‑Based Solar Cells with >6% Efficiency

In the article at ACS Applied Materials and Interfaces (DOI:10.1021/acsami.0c16634), a mixed electron transport layer (ETL) composed of ZnO nanoparticles and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) is incorporated into inorganic black orthorhombic (B-γ) CsSnI3 PSCs. The mixed ETL exhibits merits of both ZnO and PCBM. As a result, the highest PCE of 6.08% was recorded for the PSC with mixed ZnO-PCBM ETL, which is 34.2% higher than that of device with plain PCBM ETL (PCE of 4.53%) and 28.8% higher than that of device with plain ZnO ETL (PCE of 4.72%).

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Biodegradable Materials and Green Processing for Green Electronics

In the article at Advanced Materials (DOI:10.1002/adma.202001591), recent research progress in biodegradable materials and green processing for green electronics is comprehensively. The biodegradable materials used for different functional layers and green/nontoxic processing for solar cells, organic field‐effect transistors, light‐emitting devices, and other devices are discussed in detail. Future development and a perspective of green electronics are also proposed and presented.

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Hole Transporting Materials by “Flexible Core with Tunable Conformation (FCTC)” strategy for Perovskite Solar Cell

In the article at Solar RRL (DOI:10.1002/solr.202000327), new dopant-free hole transporting materials (HTMs) are designed based on “flexible core with tunable conformation (FCTC)” strategy for perovskite solar cell. With the flexible core, the HTMs can tune their configurations based on the interactions between side arms and perovskite or interactions between side arms themselves, which may lead to a good balance of mobility and charge recombination.

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Water-dispersible Conducting Polyazulene for Thermoelectrics

In the article at ChemComm (DOI:10.1039/d0cc03840g), water-dispersible conducting polymer polyazulene-polystyrenesulfonate (PAZ:PSS) is synthesized using PSS as template. PAZ:PSS can achieve overall conductivity up to 0.1 Scm-1,  and ion Seebeck coefficient as high as 4,500 μVK-1, demonstrating that PAZ:PSS is another promising water-dispersible polymer for thermoelectrics.

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High-Performance Inverted Planar Perovskite Solar Cells Enhanced by Thickness Tuning of New Dopant-free Hole Transporting Layer

In the article at Small (DOI:10.1002/smll.201904715), a new hole transporting material (HTM) 4,4',4'',4'''-([9,9'-bifluorenylidene]-2,2',7,7'-tetrayl)tetrakis(N,N-bis(4-methoxyphenyl)aniline) named DMZ is synthesized and employed as a dopant-free HTM in inverted planar perovskite solar cells (PSCs). Systematic studies demonstrate that the thickness of HTL can effectively enhance the morphology and crystallinity of perovskite layer, leading to low series resistance and less defects in the crystal. As a result, the champion power conversion efficiency (PCE) of 18.61% is achieved with a thickness of ~ 13 nm of DMZ (2 mg/mL) under standard AM 1.5G illumination,

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Passivation of Perovskite with Organophosphorus Ligands

In the article at Solar Energy Materials and Solar Cells (DOI:10.1016/j.solmat.2020.110527), organophosphorus ligands, trioctylphosphine oxide (TOPO) and triphenylphosphine oxide (TPPO), are used as passivators through antisolvent process for the interfacial modification. The organophosphorus ligands can effectively passivate the defects of perovskite crystals through the formation of Pb-O bond between organophosphorus ligand and undercoordinated Pb2+ ion in perovskite. Moreover, benzene rings with pi-electron in TPPO facilitate the charge transfer between perovskite and hole-transporting layer,  achieving the best power conversion efficiency of 18.29% with negligible hysteresis.

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Passivation of Perovskite with Fluorinated Polymer

In this work, we applied dithienobenzodithiophene-based π-conjugated polymer consisting of fluorinated benzotriazole and benzothiadiazole through anti-solvent method to passivate the defects of perovskite crystals. The fluorinated polymer interacts with under coordinated Pb2+ ions in the perovskite crystals to form Pb-F bond which effectively passivates the defects. As a result, a power conversion efficiency (PCE) of 18.03% is achieved in the champion cell. Moreover, the defect passivation blocks the pathway for moisture to diffuse into perovskite film, preventing the decomposition of the perovksite crystal. Therefore, the device retains 90% of the original PCE even after storing in an ambient environment with 60% relative humidity for 1000 h. The related work was published in Solar RRL, DOI: 10.1002/solr.201900029 and highlighted at MaterialsViewsChina (https://www.materialsviewschina.com/2019/03/35455/)

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Saddle-shaped Small Molecule as Bi-functional Hole Transporting Layer (HTL) 

In the collaboration work with Prof Li Gongqiang from Nanjin Tech University, we design and synthesize a saddle-shaped organic small molecule named α, β-COTh-Ph-OMeTAD. This bi-functional small molecule serves as a dopant-free HTL as well an interfacial layer to passivate the perovskite. With the dopant-free α, β-COTh-Ph-OMeTAD as a HTM and an interfacial layer, the perovskite solar cells (PSCs) exhibits a power conversion efficiency PCE of 17.22%, which is higher than that of device based-on conventional, doped spiro-OMeTAD (16.83%). Our work opens a new avenue for efficient and stable PSCs by exploring new dopant-free materials as alternatives to spiro-OMeTAD. The related work was published in Solar RRL, DOI:10.1002/solr.201900011

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E-skin Project by Undergraduate Students

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Kyaw Research Group