POCl3 diffusion is currently the de facto standard method for industrial n-type emitter fabrication. In this study, we present the impact of the following processing parameters on emitter formation and electrical perf...POCl3 diffusion is currently the de facto standard method for industrial n-type emitter fabrication. In this study, we present the impact of the following processing parameters on emitter formation and electrical performance： deposition gas flow ratio, drive-in tempera- ture and duration, drive-in O2 flow rate, and thermal oxidation temperature. By showing their influence on the emitter doping profile and recombination activity, we provide an overall strategy for improving industrial POCl3 tube diffused emitters.展开更多
Previously we have shown that POCl3-mediated H-bonding-directed one-pot macrocyclization allows for the highly selective preparation of five-residue macrocycles as the predominant product with low yields of hexamers a...Previously we have shown that POCl3-mediated H-bonding-directed one-pot macrocyclization allows for the highly selective preparation of five-residue macrocycles as the predominant product with low yields of hexamers and an undetectable occurrence of both tetramers and heptamers.Replacing the interiorly arrayed methyl groups with ethyl groups in these 4-7 residue macrocycles alters the relative stability order among them.Specifically,ethoxy-substituted six-residue macrocycle,rather than pentamer,turns out to be computationally the most stable,suggesting that ethoxy-containing hexamer possibly can be formed as the major product under suitable conditions.We have investigated this possibility by varying reaction temperatures and concentrations,invariably affording pentamer as the major macrocycle with strained circular hexamers and highly strained circular heptamers produced in substantial amounts.This discrepancy can be reasonably explained on the basis of bimolecular reactions between two oligomers higher than monomers via kinetic simulations.In this scenario,the acyclic pentamer is kinetically "trapped" to undergo an intramolecular cyclization to yield circular pentamer,rather than to produce acyclic hexamer.As a result,acyclic hexamer precursor is generated largely from sterically demanding bimolecular reactions between a dimer and a tetramer,or between two trimers that are kinetically slower than the pentamer-producing chain-growth reactions.We additionally found that one-pot macrocyclization proceeds to the largest extent at 40 ℃,an intriguing finding that highlights the low reactivities of acid chloride and amine groups in these H-bond-enforced acyclic oligomeric intermediates.展开更多
采用化学交联的方法对多孔淀粉进行结构上的强化。通过比较三氯氧磷、三偏磷酸钠、混合酸(柠檬酸和乙酸酐按一定的比例混合)三种交联淀粉的方法,以混合酸交联法效果最好,可明显提高多孔淀粉结构性能,其冻融稳定性、抗老化性、抗剪切性...采用化学交联的方法对多孔淀粉进行结构上的强化。通过比较三氯氧磷、三偏磷酸钠、混合酸(柠檬酸和乙酸酐按一定的比例混合)三种交联淀粉的方法,以混合酸交联法效果最好,可明显提高多孔淀粉结构性能,其冻融稳定性、抗老化性、抗剪切性等方面都最好。其最佳条件为:混合酸加入量为淀粉干重的5%,柠檬酸?乙酸酐(g/mL)为:1∶30,温度40℃,时间120 m in。所得的交联多孔淀粉的交联度程度较原多孔淀粉提高27.61%。展开更多
文摘POCl3 diffusion is currently the de facto standard method for industrial n-type emitter fabrication. In this study, we present the impact of the following processing parameters on emitter formation and electrical performance： deposition gas flow ratio, drive-in tempera- ture and duration, drive-in O2 flow rate, and thermal oxidation temperature. By showing their influence on the emitter doping profile and recombination activity, we provide an overall strategy for improving industrial POCl3 tube diffused emitters.
文摘Previously we have shown that POCl3-mediated H-bonding-directed one-pot macrocyclization allows for the highly selective preparation of five-residue macrocycles as the predominant product with low yields of hexamers and an undetectable occurrence of both tetramers and heptamers.Replacing the interiorly arrayed methyl groups with ethyl groups in these 4-7 residue macrocycles alters the relative stability order among them.Specifically,ethoxy-substituted six-residue macrocycle,rather than pentamer,turns out to be computationally the most stable,suggesting that ethoxy-containing hexamer possibly can be formed as the major product under suitable conditions.We have investigated this possibility by varying reaction temperatures and concentrations,invariably affording pentamer as the major macrocycle with strained circular hexamers and highly strained circular heptamers produced in substantial amounts.This discrepancy can be reasonably explained on the basis of bimolecular reactions between two oligomers higher than monomers via kinetic simulations.In this scenario,the acyclic pentamer is kinetically "trapped" to undergo an intramolecular cyclization to yield circular pentamer,rather than to produce acyclic hexamer.As a result,acyclic hexamer precursor is generated largely from sterically demanding bimolecular reactions between a dimer and a tetramer,or between two trimers that are kinetically slower than the pentamer-producing chain-growth reactions.We additionally found that one-pot macrocyclization proceeds to the largest extent at 40 ℃,an intriguing finding that highlights the low reactivities of acid chloride and amine groups in these H-bond-enforced acyclic oligomeric intermediates.
文摘采用化学交联的方法对多孔淀粉进行结构上的强化。通过比较三氯氧磷、三偏磷酸钠、混合酸(柠檬酸和乙酸酐按一定的比例混合)三种交联淀粉的方法,以混合酸交联法效果最好,可明显提高多孔淀粉结构性能,其冻融稳定性、抗老化性、抗剪切性等方面都最好。其最佳条件为:混合酸加入量为淀粉干重的5%,柠檬酸?乙酸酐(g/mL)为:1∶30,温度40℃,时间120 m in。所得的交联多孔淀粉的交联度程度较原多孔淀粉提高27.61%。
