Multifunctional SWCNT‐ZnO Nanocomposites for Enhancing Performance and Stability of Organic Solar Cells

Photovoltaic systems have been extensively studied and, among them, organic solar cells (OSCs) have attracted particular attention due to their low price and the possibility of using them in fl exible devices. [ 1–4 ] One of the disadvantages of OSCs is their low chemical stability, which is due to the oxidation of their interfaces by oxygen and water and the photodegradation of the active layers. [ 5–9 ] In order to increase their stability, various methods have been employed. Oxygen and water diffusion barriers were employed to protect the interfaces of OSCs from degradation. [ 10 , 11 ] Recently, an OSC with an inverted structure was developed, which was shown to be more stable than conventional solar cells. [ 12 , 13 ] In conventional structures, holes are injected into the transparent conducting electrode (TCE) and, in many cases, materials such as PEDOT: PSS with a high capability of hole injection are deposited on the TCE. In the inverted structure, in contrast, electrons are injected into the TCE. In the past, the improved stability of the inverted structure based on n-type ZnO layers on a TCE with respect to that of conventional OSCs was reported. [ 12 , 13 ] Carbon nanotubes (CNTs) have been widely used in photovoltaic systems. In many cases, bare CNTs and CNTs combined with C 60 , semiconductive and metallic nanoparticles were incorporated in the active layers, and the high capability of CNTs for electron transport has been exploited. [ 14–20 ] On the other hand,