室溫一步合成檸檬酸包覆之超小氧化鐵奈米粒子並應用於活體核磁共振T1顯影劑  合成不同組成之合金與核/殼結構量子點應用於高分子-量子點混合物  量子點太陽能電池之文獻統整

本論文成功發展於室溫且水相環境中，使用單一金屬前驅物與檸檬酸一步合成超小氧化鐵奈米粒子。檸檬酸為天然的抗氧化劑且高生物相容性高與生物可降解，作為前驅物之過鐵酸鉀為強氧化劑且已被用於廢水處理。所合成之超小氧化鐵奈米粒子具有極低磁性且能夠良好方分散在水中，因此具有極低的r2遲緩速率(1.22 mM-1s-1)與r2/r1比(1.3)，此兩種性質滿足理想MRI-T1顯影劑的條件。令人驚奇的是，此粒子可以避開單核吞噬細胞系統，增加在體內的停留時間並成功顯影腦部血管，則可幫助判別腦部血栓。此外，T1-和T2-性質可以經由小鼠的腎臟MRI證實，可以幫助辨別其表層、髓質與生理功能。此新開發的超小氧化鐵奈米粒子可以由簡單的合成步驟製備，並具有低毒性與高MRI顯影效果。半導體奈米粒子因為具有低成本、可使用濕製程技術控制與可調性的光電性質，所以已經被廣泛應用於各領域。本實驗使用熱注射法合成合金與核/殼結構之半導體奈米粒子，其放光波長涵蓋可見光至近紅外光波段，並且可以經由不同的組成與結構調控，例如：CdSe/ZnS, CdS/ZnS, CdTe/CdSe/ZnS與PbS。其中鎘系的半導體奈米粒子在經由配體置換修飾後，可以與不同的高分子單體與寡聚物混合，且在固化後保持良好的分散性。在太陽能電池的研究中，奈米科學與奈米材料提供許多能夠以低成本提高轉換效率的方法。量子侷限效應材料可以經由多激子生成、光子下轉換與光子上轉換擴大吸收波段，則能夠更完全地吸收太陽光。粒子表面與元件中各介面的化學修飾則能夠以低成本提高電子-電洞分離與收集的效率。在此統整量子點太陽能電池目前的發展與面對的難題。

關鍵字

量子點；超小奈米粒子；核磁共振顯影劑

並列摘要

The room-temperature, aqueous-phase synthesis of ultrasmall iron-oxide nanoparticles with citric acid is reported. The facile, one-step reaction involves citric acid as a capping agent and K2FeO4 as the single precursor; citric acid is a natural anti-oxidant with biocompatibility and biodegradability while K2FeO4 has been employed in the wastewater treatment as a strong oxidant for organic contaminants and as a biocide due to its unique property suited to the green chemistry. The ultra-small size caused low magnetization and great water-dispersibility, such that the resulting ultrasmall iron-oxide nanoparticles exhibit a low r2 relaxivity (1.22 mM-1s-1) and r2/r1 ratio (1.3)—both of which are critical for T1 contrast agents. This, together with the well biocompatibility, makes these clusters an ideal candidate to be a T1 contrast agent. Surprisingly, the iron-oxide clusters escape ingestion by the hepatic reticuloendothelial system, enabling strong vascular enhancement at the internal carotid artery and superior sagittal sinus, where detection of the thrombus is critical for diagnosing a stroke. Moreover, serial T1- and T2- weighted time-dependent MR images are resolved for mice’s kidneys, unveiling detailed cortical-medullary anatomy and renal physiological functions. The newly developed ultrasmall iron-oxide nanoparticles thus pave a new dimension of MRI contrast agents with facile synthesis, low toxicity, high performance and long-circulating span. Colloidal semiconductor nanocrystals possess compelling benefits of low-cost, large-scale solution processing, and tunable optoelectronic properties through controlled synthesis and surface chemistry engineering. These merits make them promising candidates for a variety of applications. Herein, different types of alloyed and core/shell quantum dots were synthesized by hot-injection method. Their emission wavelength is tunable from violet to near infrared by different composition and structure including CdSe/ZnS, CdS/ZnS, CdTe/CdSe/ZnS and PbS. After ligand exchange, the Cd-based quantum dots are able to mix with different monomers and oligomers. Then, we make a success of good dispersion after polymerization. Nanochemistry and nanomaterials provide numerous opportunities for a new generation of photovoltaics with high energy conversion efficiencies at low cost. Quantum-confined nanomaterials can harvest sun light over a broad range of the spectrum by multiple exciton generation, photon down-conversion, and photon up-conversion. Interface engineering of nanoparticle surfaces and junction-interfaces enable enhanced charge separation and collection. In this review, we survey these recent advances for improving the solar energy conversion efficiency, and reduce the device fabrication cost. It then describes the challenges and opportunities in photovoltaics where the chemical community can play a vital role.