Surface Engineering of Low-Temperature Processed Mesoporous TiO2 via Oxygen Plasma for Flexible Perovskite Solar Cells.

A major problem in the application of mesoporous TiO2 as an electron transport layer for flexible perovskite solar cells is that a high-temperature sintering process is required to remove organic additives from the TiO2 layer. A facile oxygen plasma process is herein demonstrated to fabricate mesoporous-structured perovskite solar cells with significant photovoltaic performance at low temperatures. When the low-temperature processed TiO2 layer is modified via oxygen plasma, the organic additives in the TiO2 layer that hinder the charge transport process are successfully decomposed. The oxygen plasma treatment improves the wettability and infiltration of the perovskite layer and also passivates the oxygen vacancy related traps in TiO2. Hence, the oxygen plasma treatment evidently enhances charge extraction and transport, thereby improving photovoltaic performance and decreasing hysteresis.

Facile Interfacial Engineering of Mesoporous TiO2 for Low-Temperature Processed Perovskite Solar Cells.

The mesoporous TiO2 nanoparticle-based scaffold structure is the best electron transport layer (ETL) for perovskite solar cells (PSCs) and is still used in most PSCs with optimal photovoltaic characteristics. However, the high sintering temperature of TiO2 nanoparticles required to remove binders from the TiO2 paste limits PSC application to flexible electronics. In this study, a simple interface modification process involving ethanol rinsing is developed to enhance the photovoltaic characteristics of low-temperature processed PSCs. This easy and fast technique could enable remarkable performance by PSCs by significantly increasing the fill factor and current density, leading to a power conversion efficiency more than four times that of untreated solar cells.

Enhancing Thermal Oxidation Stability of Silver Nanowire Transparent Electrodes by Using a Cesium Carbonate-Incorporated Overcoating Layer.

Despite their excellent electrical and optical properties, Ag nanowires (NWs) suffer from oxidation when exposed to air for several days. In this study, we synthesized a Cs carbonate-incorporated overcoating layer by spin-coating and ultraviolet curing to prevent the thermal oxidation of Ag NWs. Cs incorporation increased the decomposition temperature of the overcoating layer, thus enhancing its thermal resistance. The effects of the Cs carbonate-incorporated overcoating layer on the optoelectrical properties and stability of Ag NWs were investigated in detail. The Ag NW electrode reinforced with the Cs carbonate-incorporated overcoating layer exhibited excellent thermal oxidation stability after exposure to air for 55 days at 85 °C and a relative humidity of 85%. The novel overcoating layer synthesized in this study is a promising passivation layer for Ag NWs against thermal oxidation under ambient conditions. This overcoating layer can be applied in large-area optoelectronic devices based on Ag NW electrodes.

Cross-buckled structures for stretchable and compressible thin film silicon solar cells.

Increasing interests in stretchable electronic devices have resulted in vigorous research activities, most of which are focused on structural configurations. Diverse structural configurations are available for stretchability, including stiff-island, serpentine, and buckled structures. With easily deformable shapes and simple fabrication processes, buckled structures have the potential to realize stretchability. However, conventional buckled structures exhibit stretchability only in a single-axis direction. In the present study, a new type of cross-buckled structure, which can overcome the limitations of conventional buckled structures is developed. The stretchable thin film solar cells with the cross-buckled structure showed stable mechanical and electrical characteristics under both stretching and compressing conditions. The cross-buckled structure for stretchable electronic devices is expected to broaden the fields of wearable electronics, stretchable displays, and biocompatible applications.