Organic Solar Cells Based on WO2.72 Nanowire Anode Buffer Layer with Enhanced Power Conversion Efficiency and Ambient Stability

Abstract

Tungsten oxide as an alternative to conventional acidic PEDOT:PSS has attracted much attention in organic solar cells (OSCs). However, the vacuum-processed WO layer and high-temperature sol-gel hydrolyzed WO are incompatible with large-scale manufacturing of OSCs. Here, we report for the first time that a specific tungsten oxide WO (WO) nanowire can function well as the anode buffer layer. The nw-WO film exhibits a high optical transparency. The power conversion efficiency (PCE) of OSCs based on three typical polymer active layers PTB7:PCBM, PTB7-Th:PCBM, and PDBT-T1:PCBM with nw-WO layer were improved significantly from 7.27 to 8.23%, from 8.44 to 9.30%, and from 8.45 to 9.09%, respectively compared to devices with PEDOT:PSS. Moreover, the photovoltaic performance of OSCs based on small molecule p-DTS(FBTTh):PCBM active layer was also enhanced with the incorporation of nw-WO. The enhanced performance is mainly attributed to the improved short-circuit current density (J), which benefits from the oxygen vacancies and the surface apophyses for better charge extraction. Furthermore, OSCs based on nw-WO show obviously improved ambient stability compared to devices with PEDOT:PSS layer. The results suggest that nw-WO is a promising candidate for the anode buffer layer materials in organic solar cells.

Light Management in Organic Photovoltaics Processed in Ambient Conditions Using ZnO Nanowire and Antireflection Layer with Nanocone Array

“…For example, it has been shown that by introducing a buffer layer between the active layer and electrodes, it is possible to modify the band alignment and reduce the undesired charge carrier recombination sites . Several alternative buffer layers have been utilized in OPV such as PEDOT:PSS, MoO 3 , WO 3, etc., for this purpose …”

Role of Central Metal Ions in 8‐Hydroxyquinoline‐Doped ZnO Interfacial Layers for Improving the Performance of Polymer Solar Cells

“…Major benefits of OSCs include potentially low cost, compatibility with large‐area production methods, a lightweight structure, and a relatively short energy payback time . Previous studies have conducted the intensive research to extend the OSCs absorption range by modifying their photoactive layer, which has comprised highly functional novel donor, and the acceptor materials . New interfacial device architectures with appropriate doping materials have been explored for future commercial applications …”

“…Organic materials with suitable electrical and optical properties contribute to the scalability of OSC features . The cathode interfacial materials play a critical role in circumventing the shortcomings of the cathode transport layer (CTL), such as instability, low charge transportation, and weak physical contact .…”

Fabrication of WO2.72/UiO‐66 nanocomposites and effects of WO2.72 ratio on photocatalytic performance: judgement of the optimal content and mechanism study

“…owing to their localized states in the band gap and significantly different optical and electrical transport properties . Among the tungsten sub‐oxides, monoclinic WO 2.72 , also expressed as W 18 O 49 , has received considerable attention thanks to its distinctive oxygen defect structure and intense near‐infrared photo‐absorption . Furthermore, optically or electrically induced variation of the charge state of oxygen vacancy in the structure of WO 2.72 should cause a change in the sample absorption properties and thus in the coloration .…”

“…[16][17][18] Among the tungsten sub-oxides, monoclinic WO 2.72 , also expressed as W 18 O 49 , has received considerable attention thanks to its distinctive oxygen defect structure and intense near-infrared photo-absorption. [19][20][21] Furthermore, optically or electrically induced variation of the charge state of oxygen vacancy in the structure of WO 2.72 should cause a change in the sample absorption properties and thus in the coloration. 22 Unfortunately, to our knowledge, no composites of WO 2.72 and MOFs have been reported until now.…”