ABSTRACT
Organic solar cells (OSCs) are promising renewable energy sources for replacing fossil fuels. The power conversion efficiency (PCE) of OSCs has increased based on tremendous effort in material and device engineering. Still, the stability of OSC, such as long lifetime, negative temperature coefficient, must be enhanced for commercialization. In this study, we investigated OSC performance at a high operating temperature near 300-420 K, which are typical temperature regions in photovoltaic applications, with a different hole-extraction layer (HEL). The metal oxide-based HEL, MoO3, exhibited stable operating properties with a PCE drop rate of -0.13%/°C, as compared to polymeric HEL, PEDOT:PSS (-0.20%/°C). This performance reduction of polymeric HEL originated from the degradation of the interface in contact with PEDOT:PSS, as compared to the robust inorganic metal oxide HEL.
ABSTRACT
Colloidal quantum-dot-based light-emitting diodes (QD-LEDs) have gained tremendous attention as great candidates to potentially replace current emissive display technologies. The luminescence efficiency of a QD LED has increased rapidly in the past decade; this was triggered by the use of metal oxides in the charge transport layers, particularly zinc oxide (ZnO) for the electron transport layer (ETL). However, the ZnO ETL often results in undesirable device performance such as efficiency roll-off and poor device stability because of excessive electron injection into the QD emissive layer. Here, we explore solution-processable tin dioxide (SnO2) nanoparticles (NPs) as alternatives to ZnO NPs for the ETL in QD-LEDs. We evaluated the thin-film quality and electrical performance of SnO2 NPs and then applied them to the ETL for constructing QD-LEDs. As a result of the smooth surface morphology, moderate electron-transport ability, and lower carrier concentration compared to ZnO NPs, the QD-LED with SnO2 NP-ETL exhibited improved performance in terms of lower turn-on and operating voltages, maximum luminance, improved efficiency roll-off, and improved power efficiency over the reference device with the ZnO NP-ETL. This shows promising potential for SnO2 NPs in optoelectronic applications.
ABSTRACT
We develop a simple method to synthesize nano tube or wire structure of tin-oxide for gas sensor application. It is realized by the rheotaxial growth and thermal oxidation (RGTO) of tin on porous single-wall carbon nanotubes (SWNTs) as a template. The morphology and chemical property of thus formed nanostructures are examined. The electrical and NO(x) gas sensing properties are also investigated. The sensor exhibits a fast response time of less than 100 seconds and a good recovery. A sensing response of 23,400% to 10 ppm concentration at 200 degrees C is observed.
