Anode Interlayer Design in Organic Solar Cells

• Main Authors: Jan Golder, 陽哥德
• Other Authors: Chen, Chin-Ti
• Format: Others
• Language: en_US
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/7c75h2

博士 === 國立交通大學 === 應用化學系碩博士班 === 107 === The control and design of the interface between electrodes and main light absorbing materials in organic solar cells (OSCs) is a crucial factor towards improving cell characteristics and performance. Thus, since the early days of research into OSC, interlayer or buffer materials are sandwiched between the photoactive layers and the anode. The objective of this work is to design anode interlayer (AIL) and AIL materials enhancing OSC performance. This thesis consist of five chapters. The first chapter will give an overview of global energy needs, advantages of OSCs, current cell types and concepts. In the following basic working principles, interlayer concepts and established material design guidelines will be laid out. The subsequent chapter will desribe the experimental instruments, measurements, analysis methods as well as the fabrication details of devices will be explored. In the third chapter three novel small molecular materials are designed and synthesized. These materials have a rather narrow optical bandgap of around 2 eV and essentially match the lowest unoccupied molecular orbital (LUMO) of boron subphthalocyanine chloride (SubPc), the OSC donor material in this work. Upon insertion of any AIL into SubPc/C60 PHJ cell architecture the power conversion efficiencies are increased from 3.98% without AIL to as high as 4.92% with a 1,4-bis(β-cyano-p-bromostyryl)benzene (NP-β-PCN) AIL. We then demonstrate that these AIL act as exciton-blocking layer (ExBL) and prevent exciton quenching at the anode interface which in turn leads to a higher short circuit current density (JSC) which is responsible for the PCE enhancement. In the fourth chapter we successfully expand our narrow bandgap AIL design concept by introducing four more energetically similar materials. Insertion of our narrowbandgap materials again resulted in universally increased PCEs without device optimization. Furthermore, two more conventional wide bandgap hole transport materials (HTM) are explored as well. In comparison to devices which employ the two conventional AIL materials we find increases in PCE and JSC to be superior. Noteworthy, a narrow bandgap, bis(biphenylamino-spirobifluorene)-fumaronitrile (FPhSPFN) AIL resulted in a PCE of 5.13%, which is the highest reported for SubPc solar cells of similar device structures. Finally, the last chapter gives a brief summary of and concluding remarks on the research presented herein.