Yasuo Shirai

Two organolead halide perovskite nanocrystals, CH(3)NH(3)PbBr(3) and CH(3)NH(3)PbI(3), were found to efficiently sensitize TiO(2) for visible-light conversion in photoelectrochemical cells. When self-assembled on mesoporous TiO(2) films, the nanocrystalline perovskites exhibit strong band-gap absorptions as semiconductors. The CH(3)NH(3)PbI(3)-based photocell with spectral sensitivity of up to 800 nm yielded a solar energy conversion efficiency of 3.8%. The CH(3)NH(3)PbBr(3)-based cell showed a high photovoltage of 0.96 V with an external quantum conversion efficiency of 65%.

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ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTHeterocyclic Betaines Exhibiting Extremely Large First Hyperpolarizability: Ab Initio and INDO/S CalculationsJiro Abe and Yasuo ShiraiView Author Information Department of Photo-Optical Engineering Faculty of Engineering, Tokyo Institute of Polytechnics Iiyama 1583, Atsugi, Kanagawa 243-02, JapanCite this: J. Am. Chem. Soc. 1996, 118, 19, 4705–4706Publication Date (Web):May 15, 1996Publication History Received18 October 1995Revised22 February 1996Published online15 May 1996Published inissue 1 January 1996https://doi.org/10.1021/ja9535017Copyright © 1996 American Chemical SocietyRequest reuse permissionsArticle Views512Altmetric-Citations72LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit Read OnlinePDF (120 KB) Get e-AlertscloseSUBJECTS:Aromatic compounds,Excited states,Optical properties,Polarity,Polarizability Get e-Alerts

This article describes the syntheses and second-order nonlinear optical (NLO) properties of novel types of polyesters containing second-order NLO active chromophores with high density, which were obtained by condensation polymerization using two comonomers with the N,N-dialkyl-4-nitroaniline or N,N-dialkyl-4-((4-cyanophenyl)azo)aniline moiety. The polyesters were synthesized by condensation polymerization between isophthalic acid derivatives and N-substituted diethanolamines using triphenylphosphine and diethyl azodicarboxylate as the condensation reagents in dimethyl sulfoxide (DMSO) or 1-methyl-2-pyrrolidinone (NMP). The obtained amorphous polyesters exhibited good solubility in common organic solvents and provided optical-quality films by spin-coating. The SHG measurements of the spin-coated films of the resulting polyesters were carried out by the Maker fringe method using a Q-switched Nd:YAG laser (1064 nm) as an exciting beam after corona-poling. One of the polyesters, which was prepared from 5-[2-(N-methyl-4-nitroanilino)ethoxy]isophthalic acid and N-[4-((4-cyanophenyl)azo)phenyl]diethanolamine, exhibited the large second-order NLO coefficient, d33, of 202 pm/V. On the other hand, a polyester containing chromophore moieties with the highest density, which was prepared from 5-{[1,3-bis[4-((4-cyanophenyl)azo)-N-methylanilino]-2-propyl]oxy}isophthalic acid and N-[4-((4-cyanophenyl)azo)phenyl]diethanolamine, exhibited good temporal stability of the second-order nonlinearity at ambient temperature.

The first hyperpolarizability, β, of one of the simplest heterocyclic pyridinium betaines, (1-pyridinio)benzimidazolate, was measured experimentally with the hyper-Rayleigh scattering technique and compared to the calculated values obtained by the semiempirical INDO/S and ab initio molecular orbital methods. Heterocyclic pyridinium betaines are characterized by their zwitterionic character where a negatively charged aromatic electron-donating group and a positively charged aromatic electron-withdrawing group are linked directly. The experimentally obtained |β| value, (115 ± 25) × 10-30 cm5 esu-1, was in good agreement with those derived from the INDO/S calculations. The first excited state was found to be characterized by a strong intramolecular charge-transfer state, where the electron transition occurs from a negatively charged aromatic electron-donating group (benzimidazole ring) to a directly linked, positively charged aromatic electron-withdrawing group (pyridinium ring). This nature of the excited state would give rise to a large difference between the dipole moments in the excited and ground states and would contribute to enlargement of β values.