UPSI Digital Repository (UDRep)
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UPSI Digital Repository (UDRep)
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| Abstract : Universiti Pendidikan Sultan Idris |
| Hybrid organic-inorganic nanocomposite materials have emerged as one of the most potential alternative candidate to silicon as future optoelectronic material due to their unique optical and electrical characteristics. However, current fabrication process involving synthesizing the pre-made nanoparticles inside the polymer matrices is tediously complex, costly and time consuming. In this research, two approaches in preparing nanocomposite thin films, in situ hybridization and ex situ hybridization, were studied and the results were compared. In situ hybridization, a novel method, where the nanoparticles were grown directly in the Poly(3-hexylthiophene) (P3HT) mixed with stearic acid layers by exposing the films to either H2S or H2Se gas. Ex situ hybridization were done by mixing pre-made CdS or CdSe quantum dots into P3HT solution. For both approaches, depositions of thin films on the solid substrate were done by employing modified Langmuir-Blodgett technique. Studies on Langmuir layer found that the film is very sensitive towards its environment where the amount of solutions, the weight percentage, and the subphase affecting the gas-liquid-solid transformation. Absorbance spectra show higher polymer crystallization for thin films exposed to H2S or H2Se gas. The peak shifting and depreciation of absorption intensity indicates the quantum confinement effect of nanoparticles formed. Photoluminescence intensity decreased with the increment of gas exposure time and quantum dots’ weight percentage. The current density-voltage measurement revealed open circuit voltage for in situ hybrid thin film nucleating CdS and CdSe is 0.56 V and 0.72 V respectively. Thin films fabricated by ex situ method possess lower Johnson noise than that of in situ. Overall, in situ hybridization has shown a better performance as compared to hybrid nanocomposite thin films fabricated using ex situ approach. These findings have given a promising future for gas exposure method to be further studied in the fabrication of hybrid organic-inorganic nanocomposite thin films for optoelectronics application. |
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