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Title:	Synthesis and characterization of CdSe and PbSe quantum dots and ZnO nanoparticles for use in solar cell
Authors:	Ubani Charles Ahamefula (P49272)
Supervisor:	Zahari Ibarahim, Dr.
Keywords:	Nanoparticles Solar cell
Issue Date:	24-Apr-2014
Description:	Sintesis titik kuantum (QDs) CdSe dan PbSe dan nanopartikel ZnO untuk digunakan dalam sel solar titik kuantum dilaporkan dalam tesis ini. Pelbagai kaedah sintesis telah digunakan untuk menyediakan alternatif kepada batasan penggunaan mereka di dalam sel solar.Titik kuantum CdSe dan PbSe telah disintesis melalui kaedah suntikan organologam dan autoklaf hidroterma pada suhu 195oC dan 170oC dan kaedah sintesis ringan pada suhu 95oC dan 70oC masing-masing. Manakala nanopartikel ZnO telah disintesis dengan kaedah pemendakan bersama dan autoklaf hidroterma pada suhu 60 oC dan kaedah sintesis sederhana pada suhu 23 oC. Kaedah Sintesis suntikan organologam, sintesis autoklaf hidroterma dan pemendakan bersama dalam tesis ini adalah kaedah yang telah diubahsuai daripada kajian terdahulu dan telah dijalankan pada suhu rendah. Satu kaedah alternatif bahan sel solar telah dihasilkan dengan kaedah sintesis sederhana dan didapati ia satu kaedah sintesis yang mudah dan selamat. Cerapan eksperimen dari sintesis sampel keadaan pepejal memberi pemahaman proses penukleusan dan pertumbuhan dalam keadaan sintesis yang berlainan. Kaedah sintesis akan menghasilkan saiz zarah yang berlainan pada suhu yang berbeza dibawah keadaan sintesis yang berlainan telah dicerap. Sampel akhir yang terhasil telah ditulin dan dicirikan. Sifat lapisan penyerap opto-elektronik diciri menggunakan spektroskopi ultralembayung-boleh nampak ( UV-Vis) spektroskopi dan spektroskopi fotopendar cahaya (PL). Sampel yang dicirikan berbeza puncak penyerapan dan pancaran optik pada panjang gelombang yang berbeza. Jurang tenaga titik kuantum CdSe dan PbSe yang diperolehi berada pada julat 1.67 eV - 2.60 eV dan 2.17 eV - 2.23 eV masing-masing. Saiz zarah titik kuantum CdSe yang diperolehi adalah dalam julat 1.9 nm hingga 3.7 nm, titik kuantum PbSe dalam julat 2.0 nm - 3.7 nm dan nanopartikel ZnO dalam julat 28.96 nm - 36.97 nm. Corak XRD titik kuantum CdSe dan PbSe dan nanopartikel ZnO diperolehi menunjukkan pantulan Bragg sedikit lebar kerana diameter zarah yang lebih kecil pada ruang kekisi berlainan d (Å). Satah hkl XRD titik kuantum CdSe adalah 1 1 1, 2 2 0 dan 3 1 1, titik kuantum PbSe adalah 1 1 1, 2 0 0, 2 2 0, 3 1 1 dan 2 2 2 manakala nanopartikel ZnO adalah 1 0 0, 0 0 2, 1 0 1, 1 0 2 dan 1 1 0. Mikroskopi daya atom (AFM) telah digunakan untuk memeriksa komposisi sampel dan kehadiran bendasing. Purata profil kekasaran permukaan filem CdSe dan PbSe adalah dalam julat 62.016 nm - 118.816 nm dan 10.093 nm – 74.100 nm masing masing manakala julat nanopartikel ZnO adalah 24.196 nm – 156.823 nm. Kestabilan titik kuantum CdSe dalam oksigen selama 18 bulan telah dinilai dan pengagglomeratan saiz zarah bergantung kepada rawatan haba pada suhu 120oC dan dikembalikan kepada saiz awal. Sampel yang disintesis digunakan untuk fabrikasi titik kuantum sel solar terpeka (QDSSC) dengan kaedah percetakan skrin. Purata profil kekasaran permukaan QDSSC adalah 49.38 nm dan ketebalan lapisan penyerap adalah 455.21 nm. Pengukuran I-V dilakukan pada suhu bilik direkodkan menggunakan meter Keithley Model 2400. Sumber cahaya (Drive Light 1000, jenis 1400-E2 / 1, Fusion Lighting, Inc.) telah ditentukur untuk memberikan lekuk setara I-V di bawah cahaya matahari. Luas efektif elektrod 0.25 cm2 di bawah cahaya 1000 mWcm-2 menghasilkan voltan litar terbuka 0.18 mV dan ketumpatan arus foto litar pintas adalah 15.3 mAcm-2. Kecekapan penukaran tenaga sel adalah 0.93% dengan faktor pengisi 0.34. Kaedah percetakan skrin dalam sintesis dan fabrikasi QDSSC akan mengurangkan kos keseluruhan sel solar dan mengurangkan risiko sintesis suhu tinggi dan risiko sedutan bahaya kompaun Cd.,Synthesis of CdSe and PbSe quantum dots (QDs) and ZnO nanoparticles for use in quantum dot sensitized solar cell (QDSSC) is reported in this thesis. Various synthesis methods were utilized to provide an alternative pathway to encircle myriads of limitations to their usage in solar cell. CdSe and PbSe QDs were synthesized by organometallic injection method and hydrothermal autoclave method at 195 oC and 170 oC and mild synthesis method at 95 oC and 70 oC. ZnO nanoparticles were synthesized by coprecipitation and the hydrothermal autoclave method both at 60 oC and mild synthesis method at 23 oC. Organometallic injection synthesis method, hydrothermal autoclave and coprecipitaion synthesis methods reported in this thesis were modified version of previous studies and were conducted at lower temperature. A "mild synthesis method" was developed in this thesis and has shown to be a convenient and safer synthesis alternative for solar cell materials. The experimental observations of the synthesized solid state samples provided insight on the nucleation and growth processes at different synthesis conditions. The synthesis methods produced different particle sizes at different temperature under different synthesis conditions and different physical changes were observed and recorded. The final samples were purified and characterized. The opto-electronic properties of the absorber layers were characterized using ultraviolet–visible spectroscopy (UV-vis) and photoluminescence (PL) spectroscopy. Various samples have different optical absorption and emission peaks at different wavelengths. The bandgap of CdSe and PbSe QDs range between 1.67 eV - 2.60 eV and 2.17 eV - 2.23 eV. The particle sizes of CdSe QDs range between 1.9 nm to 3.7 nm, PbSe QDs range between 2.0 nm to 3.7 nm and ZnO nanoparticle particle sizes were between 28.96 to 36.97 nm respectively. The XRD pattern of the QDs obtained at 2θ angle showed that CdSe and PbSe QDs and ZnO nanoparticles were synthesized and the Bragg's reflection slightly broadened due to the small particle diameter at different lattice spacing d (Å). The hkl plane of CdSe QDs were 1 1 1, 2 2 0 and 3 1 1, PbSe QDs were 1 1 1, 2 0 0, 2 2 0, 31 1 and 2 2 2 while ZnO nanoparticles were 1 0 0, 0 0 2, 1 0 1, 1 0 2 and 1 1 0 respectively. X-ray photoelectron spectroscopy (XPS) was used to check the composition of the samples and the presence of impurities. The average surface roughness profile of CdSe and PbSe film obtained using atomic force microscopy (AFM) range between 62.016 nm -118.816 nm and 10.093 nm - 74.100 nm while ZnO nanoparticle surface roughness profile range between 24.196 nm - 156.823 nm. The stability of CdSe QDs in oxygen for 18 months was evaluated and the agglomerated particle sizes were subjected to heat treatment at 120 oC and restored to the initial sizes. The synthesized samples were used to fabricate a QDSSC by screen printing. The average surface roughness profile of the QDSSC was 49.38 nm and the thickness of the absorber layer was 455.21 nm. I–V measurement performed at room temperature was monitored and recorded using a computerized Keithley Model 2400 source measurement unit. The light source (Light Drive 1000, type 1400-E2/1, Fusion Lighting, Inc.) was calibrated to give equivalent I–V curves under direct sunlight. The active electrode area of 0.25 cm2 illuminated under light power of 1000 mWcm-2 produced an open-circuit voltage of 0.18 mV and a short-circuit photocurrent density of 15.3 mAcm-2. The energy conversion efficiency of the cell was 0.93% with a fill factor of 0.34. The synthesis methods and fabrication of QDSSC by screen printing is convenient and will reduce the overall cost of solar cell, reduces the risk of high temperature synthesis and the inhalation hazards associated with Cd compound.,PhD
Pages:	271
Call Number:	TK2960.A373 2014 tesis
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Science and Technology / Fakulti Sains dan Teknologi

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