化學系
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國立臺灣師範大學化學系座落於公館校區理學院大樓。本系成立於民國五十一年，最初僅設大學部。之後於民國六十三年、七十八年陸續成立化學研究所碩士班和博士班。本系教育目標旨在培養化學專業人才與中等學校自然及化學專業師資，授課著重理論及應用性。本系所現有師資為專任教授25人，另外尚有與中央研究院合聘教授3位，在分析、有機、無機及物理化學四個學門的基礎上發展跨領域之教學研究合作計畫。此外，本系另有助教13位，職技員工1位，協助處理一般學生實驗及行政事務。學生方面，大學部現實際共322人，碩士班現實際就學研究生共174人，博士班現實際就學共55人。
本系一向秉持著教學與研究並重，近年來為配合許多研究計畫的需求，研究設備亦不斷的更新。本系所的研究計畫大部分來自國科會的經費補助。此外，本系提供研究生獎助學金，研究生可支領助教獎學金（TA）、研究獎學金（RA）和部分的個別教授所提供的博士班學生獎學金（fellowships）。成績優良的大學部學生也可以申請獎學金。
本校圖書館藏書豐富，除了本部圖書館外，分部理學院圖書館西文藏書現有13萬餘冊，西文期刊合訂本有911餘種期刊，將近約3萬冊。此外，西文現期期刊約450種，涵蓋化學、生化、生物科技、材料及其他科學類等領域。目前本系各研究室連接校園網路，將館藏查詢、圖書流通、期刊目錄轉載等功能，納入圖書館資訊系統中，並提供多種光碟資料庫之檢索及線上資料庫如Science Citation Index，Chemical Citation Index，Chemical Abstracts，Beilstein，MDL資料庫與STICNET全國科技資訊網路之查詢。
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Item Enhanced performance of photodetector and photovoltaic based on carrier reflector and back surface field generated by doped graphene(American Institute of Physics (AIP), 2012-08-13) C.-W. Chang; D.-Y. Wang; W.-C. Tan; I-S. Huang; I-S. Wang; Chia-Chun Chen; Y.-J. Yang; Y.-F. ChenWe report the influence of carrier reflector and back surface field generated by dopedgraphene on n-ZnO nanoridges/p-silicon photodetectors and silicon solar cells. It is found that the p-type graphene not only acts as an electron blocking layer, but also helps the collection of photogenerated holes. Quite surprisingly, the on/off ratio of the photodetector with the insertion of dopedgraphene can be increased by up to 40 times. Moreover, we demonstrate that typical silicon solar cells with the dopedgraphene, the cell efficiency can be enhanced by about 20%. Our approach would expand numerous applications for graphene-based optoelectronic devices.Item Low operation voltage macromolecular composite memory assisted by graphene nanoflakes(Royal Society of Chemistry, 2013-01-21) Y.-C. Lai; D.-Y. Wang; I-S. Huang; Y.-T. Chen; Y.-H. Hsu; T.-Y. Lin; H.-F. Meng; T.-C. Chang; Y.-J. Yang; Chia-Chun Chen; F.-C. Hsu; Y.-F. ChenThe trend towards simple and low-cost processing is one of the most important for macromolecular memory development. Here, bistable memory devices using a solution-processable active material, a mixture of graphene nanoflakes (GNFs) and insulating poly(vinyl alcohol) (PVA), are investigated, which serve as the first example for the direct integration of as-prepared nanoscale graphene into macromolecular memory devices through a one-step low-temperature processing method. Bistable electrical switching behavior and nonvolatile rewritable memory effects are realized by using an indium–tin-oxide/GNF–PVA/silver (ITO/GNF–PVA/Ag) sandwich structure. The resulting device exhibits low operation voltages of +1.4 V (turn-on) and −1.3 V (turn-off), which is promising for memory cells with low power consumptions. The programmable ON- and OFF-states possess a retention time of over 104 s and endure up to 107 read pulses. The carrier transport in the OFF- and ON-states follows the typical trap-limited space charge limited current and Ohmic laws, respectively. The asymmetric electrical switch behavior is therefore attributed to conducting filaments formed in the PVA layer assisted by the charged GNFs that induce the transition of the conductivity. Our study provides a potential approach for integrating as-prepared graphene into macromolecular memory devices with excellent performances through a simple solution-process.Item Enhanced charge extraction in inverted hybrid photovoltaic cells assisted by graphene nanoflakes(Royal Society of Chemistry, 2011-11-21) Y.-M. Sung; F.-C. Hsu; D.-Y. Wang; I.-S. Wang; Chia-Chun Chen; H.-C. Liao; W.-F. Su; Y.-F. ChenWe use graphene nanoflakes (GNFs) to greatly enhance the charge extraction out of a photoactive blend in inverted hybrid poly(3-hexylthiophene):(6,6)-phenyl C61butyric acid methyl ester (P3HT:PCBM)/ZnO-nanorod photovoltaic cells. Instead of a continuous film, solution processed GNFs with dimensions less than 200 nm � 200 nm are homogeneously scattered on top of the well-aligned ZnO-nanorods. Those GNFs play key roles, they serve as an electron drain to collect electron flow out to ZnO-nanorods, enhance the carrier mobility of the device and promote holes to drift toward the surface in contact with the cathode. As a result, there is a large enhancement in photocurrent and photovoltage of 35% and 27%, respectively, leading to an improved cell efficiency by up to about 100%.Item Type-II heterojunction organic/inorganic hybrid non-volatile memory based on FeS(2) nanocrystals embedded in poly(3-hexylthiophene)(IOP Publishing, 2011-07-27) C.-W. Lin; D.-Y. Wang; Y. Tai; Y.-T. Jiang; M.-C. Chen; Chia-Chun Chen; Y.-J. Yang; Y.-F. ChenElectrical bistable behaviour was demonstrated in memory devices based on n-type FeS2 nanocrystals (NCs) embedded in a p-type poly(3-hexylthiophene) (P3HT) matrix. An organic/inorganic hybrid non-volatile memory device with a type-II band alignment, fabricated by a spin-coating process, exhibited electrical bistable characteristics. The bistable behaviour of carrier transport can be well described through the space-charge-limited current model. The small amount of FeS2 NCs in this device serve as an excellent charge trapping medium arising from the type-II band alignment between FeS2 and P3HT. Our study suggests a new way to integrate non-volatile memory with other devices such as transistor or photovoltaic since the presented FeS2/P3HT offers a type-II band alignment.Item Efficient Light Harvesting by Photon Downconversion and Light Trapping in Hybrid ZnS Nanoparticles/Si Nanotips Solar Cells(American Chemical Society, 2010-10-26) C.-Y. Huang; D.-Y. Wang; C.-H. Wang; Y.-T. Chen; Y.-T. Wang; Y.-T. Jiang; Y.-J. Yang; Chia-Chun Chen; Y.-F. ChenA hybrid colloidal ZnS nanoparticles/Si nanotips p−n active layer has been demonstrated to have promising potential for efficient solar spectrum utilization in crystalline silicon-based solar cells. The hybrid solar cell shows an enhancement of 20% in the short-circuit current and approximately 10% in power conversion efficiency compared to its counterpart without integrating ZnS nanoparticles. The enhancement has been investigated by external quantum efficiency, photoluminescence excitation spectrum, photoluminescence, and reflectance to distinct the role of ZnS quantum dots for light harvesting. It is concluded that ZnS nanoparticles not only act as frequency downconversion centers in the ultraviolet region but also serve as antireflection coating for light trapping in the measured spectral regime. Our approach is ready to be extended to many other material systems for the creation of highly efficient photovoltaic devices.Item Efficient light harvesting and carrier transport in PbS quantum dots/silicon nanotips heterojunctions(IOP Publishing, 2011-03-02) C.-Y. Huang; D.-Y. Wang; C.-H. Wang; Y.-T. Wang; Y.-T. Jiang; Y.-J. Yang; Chia-Chun Chen; Y.-F. ChenLight harvesting from nanocomposites consisting of silicon (Si) nanotips and PbS quantum dots (QDs) has been investigated. We show that Si nanotips provide direct carrier transport paths, additional interfacial area and light trapping. We observe that there is a dramatic enhancement in short-circuit current (from 9.34 to 14.17 mA cm−2) with nanotips structure than that of the bulk Si wafer. In addition, with an additional electron blocking layer, the photovoltaic performance can be further increased. The nanocomposites consisting of QDs and Si nanotips therefore open a promising route for efficient light harvesting from visible to infrared with improved power conversion efficiency.Item Increased Photocurrent in Bulk-heterojunction Solar Cells Mediated by FeS(2) Nanocrystals(Elsevier, 2011-04-01) C.-W. Lin; D.-Y. Wang; Y.-T. Wang; Chia-Chun Chen; J.-Y. Yang; Y.-F. ChenWe found that the efficiency of bulk-heterojunction (BHJ) solar cells can be enhanced by incorporating a small amount of semiconductor FeS2 nanocrystals (NCs) into the poly(3-hexylthiophene) (P3HT) and (6,6)-phenyl C61-butyric acid methyl ester (PCBM) based active layer. Through optical and nanoscale structure measurements, it is evident that low-cost and non-toxic FeS2 NCs in such devices can efficiently improve charge carrier transport and exciton dissociation. This simple approach for increasing the photocurrent by NCs will be useful for accelerating the development of practical applications using organic solar cells.Item Enhanced Emission of (In, Ga) Nitride Nanowires Embedded with Self-assembled Quantum Dots(Wiley-VCH Verlag, 2008-03-25) C.-W. Hsu; A. Ganguly; C.-H. Liang; Y.-T. Hung; C.-T. Wu; G.-M. Hsu; Y.-F. Chen; Chia-Chun Chen; K.-H. Chen; L.-C. ChenWe report the structure and emission properties of ternary (In,Ga)N nanowires (NWs) embedded with self-assembled quantum dots (SAQDs). InGaN NWs are fabricated by the reaction of In, Ga and NH3 via a vapor–liquid–solid (VLS) mechanism, using Au as the catalyst. By simply varying the growth temperature, In-rich or Ga-rich ternary NWs have been produced. X-ray diffraction, Raman studies and transmission electron microscopy reveal a phase-separated microstructure wherein the isovalent heteroatoms are self-aggregated, forming SAQDs embedded in NWs. The SAQDs are observed to dominate the emission behavior of both In-rich and Ga-rich NWs. Temperature-dependent photoluminescence (PL) measurements indicate relaxation of excited electrons from the matrix of the Ga-rich NWs to their embedded SAQDs. A multi-level band schema is proposed for the case of In-rich NWs, which showed an anomalous enhancement in the PL peak intensity with increasing temperature accompanies with red shift in its peak position.Item Carrier Transfer Induced Photoluminescence Change in Metal-Semiconductor Core-Shell Nanostructures(American Institute of Physics, 2006-04-17) H.-Y. Lin; Y.-F. Chen; J.-G. Wu; D.-I. Wang; Chia-Chun ChenMetal-semiconductor core-shell nanostructures have been synthesized to explore the influence of metal nanostructures on the photoluminescence of semiconductors. Up to 40 times enhancement in the emission intensity was observed in the Au–CdS core-shell nanostructures. The mechanism where the excited electrons on Au surface by surface plasmon wave transfer to the conduction band of the CdS shell and recombine with holes in the valence band was proposed to interpret the enhancement. Our model can also be used to explain the quenched emission in FePt–CdS core-shell nanostructures and Au–CdSe nanodumbbells.Item Sharp Infrared Emission from Single-Crystalline Indium Nitride Nanobelts Prepared Using Guided-Stream Thermal Chemical Vapor Deposition(Wiley-VCH Verlag, 2006-03-01) M.-S. Hu; W.-M. Wang; T.-T. Chen; L.-S. Hong; C.-W. Chen; Chia-Chun Chen; Y.-F. Chen; K.-H. Chen; L.-C. ChenSingle-crystalline InN nanobelts have been synthesized using Au as the catalyst by a guided-stream thermal chemical vapor deposition technique. The resultant InN nanobelts typically have widths ranging from 20 to 200 nm, a width to thickness ratio of 2–10, and lengths of up to several tens of micrometers. Structural analysis shows that these InN nanobelts have a wurtzite structure and exhibit a rectangular cross section with self-selective facets, i.e., the nanobelts are enclosed only by ± (001) and ± (11?0) planes with [110] being the exclusive growth direction along their long axis. This facet selectivity can be understood by the differences in the surface energies of the different facets. Photoluminescence (PL) spectra of InN nanobelts show a sharp infrared emission peak at 0.76 eV with a full width at half maximum of 14 meV, narrower than the values reported for InN epilayers. The integrated PL intensity is found to increase linearly with the excitation power, which suggests that the observed PL can be attributed to direct band-to-band emission.