Date of Award
Doctor of Philosophy
Materials Science and Engineering
Roberto S. Benson, David Mandrus, Brian Long
Organic polymer and organo-metal halide perovskite (OMHP) materials have attracted extensive attention during the past decade due to their various applications, like solar cells, light emitting diode, even lasing action (OMHP). Especially, the organo-metal halide perovskite solar cell shows a remarkable power conversion efficiency of about 20%, which is comparable to the amorphous silicon solar cell. Therefore, OMHP solar cell had been considered as a promising substitution for the next generation of renewable energy source. The OMHP materials contain both advantages of organic and inorganic semiconductors, like solution processable thin film fabrication, long-range ambipolar transport characteristics, high dielectric constants, low exciton binding energies, and direct bandgap. In this dissertation, Chapter 1 has been separated into two parts. First part presents an introduction for different types of photovoltaic materials, including inorganic, organic, and OMHPs semiconductors. Second part introduces the device fabrication of organic solar cells, OMHP solar cells, and OMHP light emitting diodes. Chapter 2 shows the effect of dipole-dipole interaction between electron donor (PTB7) and electron acceptor (PCBM) in polymer based organic bulk heterojunction solar cell. Here, optically induced dipole-dipole interaction can largely decrease the electron-hole binding energy at donor:acceptor (D:A) based on the PTB7:PCBM bulk-heterojunctions. Chapter 3 demonstrates a systematically study of spin dependent photo-generated e-h pairs recombination and dissociation processes in OMHP solar cells by using external magnetic field combining with photocurrent (PC) and photoluminescence (PL). In Chapter 4, the effect of interfacial layer on photovoltaic performance in OMHP solar cells will be demonstrated. Meanwhile, impedance measurement and e-h binding energy measurement will be used to demonstrate how the interfacial dipole to affect the interfacial and bulk properties in OMHP solar cells. Chapter 5 presents the study of pure free charge recombination processes as a function of different densities of injection current by utilizing OMHP light emitting diodes. Chapter 6 study the current amplification and luminescence curve shape narrowing phenomenon from OMHP devices under a simultaneously applied electrical excitation and photoexcitation. Finally, Chapter 7 summarizes a conclusion for the entire dissertation.
Hsiao, Yu-Che, "Magnetic, Optical and Electrical Properties of Electron-Hole Pairs in Polymer and Organo-Metal Halide Perovskite Photovoltaic cells. " PhD diss., University of Tennessee, 2016.