Jwu-Ting Chen

Surface passivation of Cu(In,Ga)Se2 using atomic layer deposited Al2O3

With Al2O3 passivation on the surface of Cu(In,Ga)Se2, the integrated photoluminescence intensity can achieve two orders of magnitude enhancement due to the reduction of surface recombination velocity. The photoluminescence intensity increases with increasing Al2O3 thickness from 5 nm to 50 nm. The capacitance-voltage measurement indicates negative fixed charges in the film. Based on the first principles calculations, the deposition of Al2O3 can only reduce about 35% of interface defect density as compared to the unpassivated Cu(In,Ga)Se2. Therefore, the passivation effect is mainly caused by field effect where the surface carrier concentration is reduced by Coulomb repulsion.

Biscarbene palladium(II) complexes. reactivity of saturated versus unsaturated N-heterocyclic carbenes.

A series of designed palladium biscarbene complexes including saturated and unsaturated N-heterocyclic carbene (NHC) moieties have been prepared by the carbene transfer methods. All of these complexes have been characterized by (1)H and (13)C NMR spectroscopy as well as X-ray diffraction analysis. The reactivity of Pd-C((saturated NHC)) is distinct from that of Pd-C((unsaturated NHC)). The Pd-C((saturated NHC)) bonds are fairly stable toward reagents such as CF(3)COOH, AgBF(4) and I(2), whereas Pd-C((unsaturated NHC)) bonds are readily cleaved under the similar conditions. Notably, the catalytically activity of these palladium complexes on Suzuki-Miyaura coupling follows the order: (sat-NHC)(2)PdCl(2) > (sat-NHC)(unsat-NHC)PdCl(2 )> (unsat-NHC)(2)PdCl(2).

Synthesis and characterization of PdII-methyl complexes with N-heterocyclic carbene-amine ligands

A number of palladium(ii) complexes with a heteroditopic NHC-amine ligand and their precursor silver(i) carbene complexes have been efficiently prepared and their structural features have been investigated. The heteroditopic coordination of this ligand class was unequivocally shown by NMR-spectroscopy and X-ray crystallographic analysis. The neutral and cationic cis-methyl-palladium(NHC) complexes are not prone to reductive elimination, which is normally a major degenerative pathway for this type of complex. In contrast, under carbon monoxide atmosphere rapid reductive elimination of the acyl-imidazolium salt was observed.

A new stable intermediary mode between η3-2-aminoallyl complexes and metallacyclobutanimines. Synthesis and structural characteristic of η3-azatrimethylenemethane and N-protonated, N-alkylated, N-arylated η3-azatrimethylenemethane complexes of Pt and Pd

Regioselective addition of ammonia, primary or secondary amines, aniline, or amino derivatives either to a neutral ( η 1 -allenyl)platinum complex trans -Pt(Br)(PPh 3 ) 2 ( η 1 -CHCCH 2 ) ( 1 ) or to a cationic η 3 -allenyl/propargyl platinum complex [Pt(PPh 3 ) 2 ( η 3 -C 3 H 3 )](BF 4 ) ( 2 ) provide the synthesis of cationic N -protonated, N -alkylated, and N -arylated η 3 -azatrimethylenemethane complexes {Pt(PPh 3 ) 2 ( η 3 -CH 2 C(NRR′)CH 2 ]}(X) (R=H R′=H ( 3a ), Me ( 3b ), Et ( 3c ), i Pr ( 3d ), t Bu ( 3e ), c-C 6 H 11 ( 3f ), Ph ( 3g ), CH 2 CH 2 OH ( 3h ), R=R′=Et ( 3i ), c-C 3 H 6 (from azetidine 3j ), Ph ( 3k ), R=Me R′=Ph ( 3l ); X=Br, BF 4 ), respectively. Addition of amides to 1 gave a neutral η 3 -azatrimethylenemethane complex Pt(PPh 3 ) 2 [ η 3 -CH 2 C(NSO 2 Ph)CH 2 ] ( 4m ). Similar reactions using palladium complexes yield {Pd(PPh 3 ) 2 [ η 3 -CH 2 C(NRR′)CH 2 ]}(X) (R=H R′= i Pr ( 7d ), Ph ( 7g ), R=R′=Et ( 7i ); X=Br, BF 4 , OTf), Pd(Br)(PPh 3 )[ η 3 -CH 2 C(NEt 2 )CH 2 ] ( 8i ) and Pd(PPh 3 ) 2 [ η 3 -CH 2 C(NR)CH 2 ] (R=SO 2 Ph ( 9m ), p -SO 2 C 6 H 4 Me ( 9n )). Synthesis of three complexes, {M(PPh 3 ) 2 [ η 3 -CH 2 C(NHR)CH 2 ]} + (M=Pt R=SO 2 Ph ( 3m ); M=Pd R=SO 2 Ph ( 7m ), p -SO 2 C 6 H 4 Me ( 7n )), can not be done by hydroamination reactions, but has been successful using protonation of η 3 - N -TMM complexes 4m , 9m , and 9n , respectively. Spectroscopic and crystallographic characterizations indicate that these N -TMM complexes exhibit intermediary structural features between η 3 -2-aminoallyl and metallacyclobutanimine complexes. 2

Coordination chemistry and catalytic activity of N-heterocyclic carbene iridium(I) complexes

Iridium complexes [(CO)2Ir(NHC-R)Cl] (R = Et-, 3a; PhCH2-, 3b; CH3OCH2CH2-, 3c; o-CH3OC6H4CH2-, 3d; NHC: N-heterocyclic carbene) are prepared via the carbene transfer from [(NHC-R)W(CO)5] to [Ir(COD)Cl]2. By using substitution with 13CO, we are able to estimate the activation energy (G) of the CO-exchange in 3a-d, which are in the range of 12-13 kcal mol-1, significantly higher than those for the phosphine analog [(CO)2Ir(PCy3)Cl]. Reactions of 3b and 3d with an equimolar amount of PPh3 result in the formation of the corresponding [(NHC-R)Ir(CO)(PPh3)Cl] with the phosphine and NHC in trans arrangement. In contrast, the analogous reaction of 3a or 3c with phosphine undergoes substitution followed by the anion metathesis to yield the corresponding di-substituted [(NHC-R)Ir(CO)(PPh3)2]BF4 (5) directly. Treatment of 3b or 3d with excess of PPh3 leads to the similar product of disubstitution 5b and 5d. The analysis for the IR data of carbonyliridium complexes provides the estimation of electron-donating power of NHCs versus phosphines. The NHC moiety on the iridium center cannot be replaced by phosphines, even 1,2-bis(diphenylphohino)ethane (dppe). All the carbene moieties on the iridium complexes are inert toward sulfur treatment, indicating a strong interaction between NHC and the iridium centers. Complexes 3a-c are active on the catalysis of the oxidative cyclization of 2-(o-aminophenyl)ethanol to yield the indole compound. The phosphine substituted complexes or analogs are less active.

Regioselective addition of chalcogenol to an η3-propargyl/allenyl complex via formation of the carbon-chalcogen bond leading to new chalcogenoxyallyl species☆

Regioselective addition of chalcogenol to an ν3-propargyl complex Pt(PPh3)2(η3-C3H3)](BF4) (2) via the formation of the CO, CS, or CSe bond generates new cationic chalcogenoxyallyl species {Pt(PPh3)2[η3CH2C(ER)CH2]}(BF4) (E = O, R = Me 4(a), Et (4b, iPr (4c), 1Bu (4d), Ph (4e); ES, EEt (5b), tBu (5d, Ph (5e); ESe, RPh (6e )) respectively in good yields. Thiol and selenol react with complex 2 much faster than alcohol; and 2 reacts with p-(HO)C6H4(SH) to exclusively yield the thioxyallyl product {Pt(PPh3)2[η3-CH2C(SC6H4OH)CH2]}(BF4) (5f). Among the alcoh and phenol, thereactivity follows the order MeOH > EtOH >, iPrOH >, tBuOH > PhOH. A mechanism comprising a preceding coordination step is postulated. The X-ray structures of 4b, 4e, 5b, 5e and 6e are provided.

Kinetic and Mechanistic Studies of Geometrical Isomerism in Neutral Square-Planar Methylpalladium Complexes Bearing Unsymmetrical Bidentate Ligands of α-Aminoaldimines

A series of hemilabile ligands of alpha-aminoaldimines and their methylpalladium complexes have been prepared and characterized. Neutral square-planar methylpalladium complexes in the form of [R(1)R(2)NCMe(2)CH horizontal lineNR]Pd(Me)Cl (R = Me, R(1) = R(2) = Me (3a); R = Me, R(1) = R(2) = Et (3b); R = Et, R(1) = R(2) = Me (4a); R = (n)Pr, R(1) = R(2) = Me (5a); R = (i)Pr, R(1) = R(2) = Me (6a); R = (i)Pr, R(1) = R(2) = Et (6b); R = (i)Pr, (R(1), R(2)) = c-C(4)H(8) (6c); R = (i)Pr, R(1) = (i)Pr, R(2) = H (6d); R = (i)Pr, R(1) = (t)Bu, R(2) = H (6e); R = (t)Bu, R(1) = R(2) = Me (7a); R = (t)Bu, R(1) = R(2) = Et (7b); R = (t)Bu, (R(1), R(2)) = c-C(4)H(8) (7c); R = (t)Bu, R(1) = (i)Pr, R(2) = H (7d); R = (t)Bu, R(1) = (t)Bu, R(2) = H (7e); R = Ph, R(1) = R(2) = Me (8a); R = Ph, R(1) = R(2) = Et (8b)) show geometrical isomerism. The relative ratios of trans/cis isomers appear to be predominated by the steric hindrance between the Pd-bound methyl group and imino or amino substituents (R and R(1) and R(2)). The NMR studies for the substitution reaction of (COD)Pd(Me)Cl with Et(2)NCMe(2)CH horizontal lineN(i)Pr at -20 degrees C indicate that cis-6b is the major kinetic product, which isomerizes to the thermodynamic product in trans form quantitatively above -5 degrees C. Kinetic results show that the ligand substitution reaction likely undergoes an associative pathway, and the isomerization reaction proceeds via an intramolecular process that comprises imine dissociation and recoordination.

Ligand effects on palladium complex catalyzed copolymerization of ethylene/carbon monoxide

Several neutral and cationic methyl palladium complexes with bidentate ligands of phosphorus–nitrogen (P∼N) donors which form five- or six-membered chelates have been synthesized and characterized. Carbonylation of these complexes generates the corresponding stable Pd–acetyl complexes. The ligands that form a five-membered chelating ring appear to confer better activity towards carbonylation as well as copolymerization of ethylene/CO than do the six-membered analogues. Crystal structures of several inserted intermediates are provided.

Plasma Charging Damage and Water‐Related Hot‐Carrier Reliability in the Deposition of Plasma‐Enhanced Tetraethylorthosilicate Oxide

This paper presents plasma-enhanced tetraethylorthosilicate oxide process (PETEOS) induced hot-carrier reliability associated with an intermetallic dielectric formed by depositing oxide films from PETEOS, ozone-TEOS, and spin-on glass (SOG), where a single or dual-frequency PETEOS film is deposited as an underlayer followed by an ozone-TEOS deposition for gap filling and a SOG coating for planarization. The impact of PETEOS process conditions such as low-and high-frequency plasma power and PETEOS film thickness on hot-carrier reliability are studied. It is observed that increasing the low- and/ or high-frequency plasma power can improve the film quality and moisture-related hot carrier immunity, but at the expense of plasma charging damage. This plasma charging damage accumulates gradually and finally saturates as the deposition of oxide from PETEOS proceeds. In general, a thick PETEOS layer is desired for improving the moisture-related hot carrier immunity. As a result, there is a trade-off between the plasma charging damage and the moisture-related hot carrier immunity. The plasma charging damage is dominant in large devices and the moisture-related hot-carrier immunity is dominant in small devices.

Coordination Chemistry of Highly Hemilabile Bidentate Sulfoxide N-Heterocyclic Carbenes with Palladium(II)

Imidazolium salts, [RS(O)-CH2 (C3 H3 N2 )Mes]Cl (R=Me (L1a), Ph (L1b)); Mes=mesityl), make convenient carbene precursors. Palladation of L1a affords the monodentate dinuclear complex, [(PdCl2 {MeS(O)CH2 (C3 H2 N2 )Mes})2 ] (2a), which is converted into trans-[PdCl2 (NHC)2] (trans-4a; N-heterocyclic carbene) with two rotamers in anti and syn configurations. Complex trans-4a can isomerize into cis-4a(anti) at reflux in acetonitrile. Abstraction of chlorides from 4a or 4b leads to the formation of a new dication: trans-[Pd{RS(O)CH2(C3H2N2)Mes}2](PF6)2 (R=Me (5a), Ph (5b)). The X-ray structure of 5a provides evidence that the two bidentate SO-NHC ligands at palladium(II) are in square-planar geometry. Two sulfoxides are sulfur- and oxygen-bound, and constitute five- and six-membered chelate rings with the metal center, respectively. In acetonitrile, complexes 5a or 5b spontaneously transform into cis-[Pd(NHC)2(NCMe)2](PF6)2. Similar studies of thioether-NHCs have also been examined for comparison. The results indicate that sulfoxides are more labile than thioethers.