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Polymeric Electron-Selective Contact for Crystalline Silicon Solar Cells with an Efficiency Exceeding 19%
摘要： Carrier-selective contacts have become a prominent path forward towards efficient crystalline silicon (c-Si) photovoltaics. Among the proposed contacting materials, organic materials may offer simplified and low-cost processing compared with typical vacuum deposition techniques. Here, branched polyethyleneimine (b-PEI) is presented as an electron-transport layer (ETL) for c-Si solar cells. The incorporation of b-PEI interlayer between c-Si(n) and Al leads to a low contact resistivity of 24 mΩ cm2. Silicon heterojunction solar cell integrated with b-PEI is demonstrated achieving a power conversion efficiency of 19.4%, which improves the benchmark efficiency of a c-Si solar cell with an organic ETL. This electron-selectivity of b-PEI is attributed to its Lewis basicity, i.e., electron donating ability, promoting favorable band bending at the c-Si surface for electron transport. Moreover, several other Lewis base polymers perform as efficient ETLs in organic/c-Si hybrid devices, indicating Lewis basicity could be a guideline for future organic ETLs design.
关键词： solar cells,crystalline silicon,polymeric electron-selective contact,b-PEI,Lewis basicity
更新于2025-09-23 15:19:57
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Photocatalytic Oxidation of Aniline over MO/TiO2 (M = Mg, Ca, Sr, Ba) under visible light irradiation
摘要： MO/TiO2 (M=Mg, Ca, Sr & Ba; TiO2: Evonik Aroxide P25) composites were prepared for photocatalytic aniline oxidation under visible light irradiation. The conversion efficiencies of aniline over the samples are revealed as follow order: BaO/TiO2>SrO/TiO2>CaO/TiO2>MgO/TiO2. The combined results of XPS and CO2 TPD indicate that the electron density of lattice oxygen and the surface basicity for the photocatalysts became higher and higher with the atomic number increase of the alkaline metal elements, in accordance with the order of the conversion efficiency. The sample SrO/TiO2 shows the highest nitrosobenzene selectivity. BaO/TiO2 with highest surface basicity may facilitate the further aniline transformation to nitrobenzene and azobenzene, resulting in lower selectivity for nitrosobenzene. Surface complexes formed on the basic sites of the catalysts via aniline chemsorption would be acted as active sites and be excited for the photocatalytic oxidation of aniline under visible light irradiation.
关键词： MO/TiO2,Surface Basicity,Photocatalytic Aniline Oxidation,Surface Complexes,Conversion and Selectivity
更新于2025-09-10 09:29:36
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UV–vis spectroscopy combined with azastilbene probe as a tool for testing basicity of mesoporous silica modified with nitrogen compounds
摘要： N-bromobenzyl substituted (E)-4′-hydroxy-4-stilbazolium bromide (NBSB), a representative of azastilbene compounds which reveals strong solvatochromism, was used as a probe molecule for testing basicity of nitrogen organic compounds grafted on mesoporous cellular foam silica (MCF). Easy deprotonation of this compound in contact with basic species was the reason for its use for probing the basicity of AP/MCF (AP - (3-aminopropyl) trimethoxysilane), Im/MCF (Im - N-trimethoxysililpropylimidazole) and Az/MCF (Az - (3-azidopropyl)(triethoxy)silane). NBSB and its deprotonated form were analyzed by UV–vis spectroscopy measurements in solutions and UV–vis in solid materials. Ab-initio calculation allowed distinction between the preference of NBSB for interactions with SiOH on the support surface and with nitrogen species of the modi?er. The NBSB protonation - deprotonation equilibrium dependence on pH was indicated. The role of solvent was considered. In water indirect probing of basicity by NBSB was observed via abstraction of proton from solvent by the modi?er and deprotonation of NBSB due to the increased pH of the solution. In acetonitrile direct basicity probing took place in which NBSB was adsorbed in MCF pores. AP/MCF and Im/MCF caused deprotonation of NBSB, as monitored by UV–vis re?ectance spectra. This e?ect was stronger for AP/MCF, which showed higher basicity. Az/MCF could not deprotonate NBSB in either water or acetonitrile.
关键词： Basicity,FTIR,Ab-initio calculations,Hydroxystilbazolium cyanines,UV–vis,Nitrogen compounds on MCF
更新于2025-09-04 15:30:14