The Study of Enhancing Power Conversion Efficiency of Organic and Perovskite Solar Cells

• Main Authors: Wen-Kai Lin, 林文凱
• Other Authors: Shui-Hsiang Su
• Format: Others
• Language: en_US
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/357ckq

博士 === 義守大學 === 電子工程學系 === 104 === The main purpose of this dissertation is to enhance the power conversion efficiency (PCE) of organic and perovskite solar cells. It includes the enhancement of performance in flexible organic solar cells (OSCs) by using a stacked hole transporting layer (HTL), the study of three various active layer in the inverted OSCs, and the study of high PCE perovskite solar cells. The dissertation is organized into three parts. The first part focuses on enhancing the short-circuit current density (Jsc) and PCE of OSCs fabricated on two various substrates, glass and PET. The stacked HTL is vanadium oxide (V2O5)/poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS). The OSC configuration comprises glass/ITO/V2O5/PEDOT:PSS /poly(3-hexylthiophene) (P3HT):phenyl C61-butyric acid methylester (PCBM)/LiF/Al. The PCE is 2.67% under simulated AM1.5G illumination of 100 mW/cm2, which is tenfold greater than that of a conventional device without the HTL. The V2O5/PEDOT:PSS stacked HTL provides a smooth film surface for coating P3HT:PCBM active layer, in addition to a stepwise hole-transporting configuration, subsequently increasing charge carrier transporting capability and extracting holes from the active layer. Employing the V2O5/PEDOT:PSS stacked HTL to fabricate OSC onto a flexible PET substrate, the optimized device exhibits an open circuit voltage (Voc) of 0.57 V, Jsc of 6.08 mA/cm2, fill factor (FF) of 44.64%, and PCE of 1.57%. It is twenty-five times greater than that of a conventional flexible OSC without the HTL. The second part discusses and characterizes three various active layers in the inverted OSCs. a) Fabricating the inverted OSCs use a whole solution process. The hole blocking layer (HBL), active layer and HTL film are all fabricated by spin-coating technique. The anode is formed from Ag nanoparticles (NPs) by drop titration using a Pasteur burette. b) Doping carbon nanotubes into the P3HT:PCBM active layer and using Ti-doped ZnO to be an HBL to reduce series resistances and enhance the PCE of inverted OSCs. c) Wide wavelength inverted OSCs are fabricated and characterized by doping the active layer with long wavelength absorbing tin (II) phthalocyanine (SnPc). The HTL comprises Ag NPs-embedded PEDOT:PSS. The Jsc and PCE are considerably enhanced. Ag NPs result in the enhancement of the scattering and reflection of light, leading to increase absorption efficiency in the active layer of inverted OSCs. Moreover, the SnPc-doped active layer exhibits long wavelength absorption and prevents the active layer from degradation by PCBM clusters. The optimized inverted OSCs exhibit a Voc of 0.50 V, Jsc of 10.34 mA/cm2, FF of 45.33%, and PCE of 2.33% under simulated AM1.5G illumination of 100 mW/cm2, respectively. In the last part, the perovskite solar cells are fabricated and characterized by both solvent treatment for the active layer and inserting a thin buffer layer. The grain of MAPbI3 active layer agglomerates owing to methylbenzene treatment and the perovskite solar cell shows a decreased series resistance (Rs). The 1,3,5-tris(N-phenylbenzimidazol-2-yl)benzene (TPBi) works as an efficient buffer layer which enhances device performance by forming improved interfacial contact and blocking the hole from transporting to the cathode. The optimized perovskite solar cell exhibits a Voc of 0.90 V, Jsc of 13.44 mA/cm2, FF of 64.69%, and PCE of 7.81% under simulated AM1.5G illumination of 100 mW/cm2, respectively.