Design, Simulation and Fabrication of Multijunction Polymer and Hybrid Solar Cells

• Other Authors: Khanam, Jobeda Jamal (author)
• Format: Others
• Language: English; English
• Published: Florida State University
• Subjects: Electrical engineering
• Online Access: http://purl.flvc.org/fsu/fd/2019_Fall_khanam_fsu_0071E_15497

In recent years, organic solar cells (OSCs) have been attracting much attention due to the ease of processing, low cost, flexibility, and lightweight compared to the traditional inorganic solar cells. Although OSC looks promising, it has some significant limitations. One limitation is the low efficiencies of the OSCs compared to silicon and III-V compound solar cells, due to limited exciton generation when the light strike on it and low electron and hole mobility. Moreover, OSC has poor stability and short lifetime, due to the degradation of the polymer/electrode interface. For improve the efficiency of PSC, several methods implemented such as annealing, device structure tuning, and active material modification, etc. Among them staking two or more organic junctions (BHJ/HJ) are called tandem structure is one of the most effective solutions. Also, the PV devices using a mixture of inorganic nanoparticle and conjugated polymers called hybrid solar cells (HSCs), has been gain popularity for absorbing near-infrared light. It is essential to tune the thickness of active layers used in tandem photovoltaic to optimize the device performance. Finding the optimum tandem structure using trial and error experiments is expensive and sometimes ineffective. Simulation is a more efficient tool to create the most suitable tandem device structure. The current-voltage (J-V) characteristics will be used to compare the results of simulation and experimental data. The transfer matrix method is implemented for optical modeling of an OSC and HSCs, which was inspired by McGehee Group MATLAB program. The program calculates optimal thicknesses active layers giving the best short circuit current (Jsc) value. It has here shown different multijunction polymer solar cell which can able to absorb sunlight beyond 1000nm. Then explained the high-efficiency hybrid (organic and inorganic) solar cell which can absorb the sunlight with wavelength beyond 2500nm. In this work, we present a novel multijunction polymer solar cell and hybrid solar cell designs. Approximately 12% efficiency obtained from multijunction polymer solar cell, and 20% efficiency from every two, three, and four junction hybrid solar cells, under one sun AM1.5 illumination. Based on the simulation results, we fabricated single-junction PbS Quantum Dot (QD) solar cell. The PbS quantum dots (QD) is a promising nanostructured material for solar cell. However, insufficient works have been done to explore the active layer thickness, stability improvement, the layer deposition techniques, and cost reduction for PbS QD solar cell. We addressed those issues of device fabrication and suggested their possible solutions. In our work, to get maximum current density from a PbS QD solar cell, we estimated optimized active layer thickness using MATLAB simulation. After that, we fabricated high performance and low-cost QD photovoltaic (PV)device with the simulated optimized active layer thickness. We implemented the low-cost device by using 10mg/ml PbS concentration. Here drop-cast layer deposition and spin coating methods were used and compared. We found that the device fabricated by the spin coating method is more efficient than the drop cast method. The spin-coated PbS QD solar cell produced 6.5% power conversion efficiency (PCE) at AM1.5 light spectrum. Besides, we observed, Cr (chromium) interfaces with the Ag (Cr- Ag) electrode can provide a high air-stable electrode. === A Dissertation submitted to the Department of Electrical and Computer Engineering in partial fulfillment of the requirements for the degree of Doctor of Philosophy. === 2019 === October 10, 2019. === Hybrid Solar Cells, Low Cost, Multijunction, PbS QD Solar Cell, Polymer Solar Cells, Stability === Includes bibliographical references. === Simon Y. Foo, Professor Directing Dissertation; Anke Meyer-Baese, University Representative; Petru Andrei, Committee Member; Shonda Bernadin, Committee Member; Zhibin Yu, Committee Member.