Controlled Alignment of Nanowires for Transparent Conductive Films: Methods and Applications

Background: Nanowires (NWs) have received extensive attention as the candidate materials for transparent conductive films (TCFs) in recent years. To date, the aligned nanowire (NW)- based TCFs with the same arrangement direction have shown superior characteristics to their random counterparts in applications. Objective: To fully develop the potential of NW TCFs in devices and provide inspiration for the development of subsequent NW alignment processes, this review summarizes state-of-the-art alignment techniques and emphasizes their mechanisms in detail from multiple perspectives. Methods: According to the mechanism of NW alignment, this review divides these techniques into seven categories, i.e., the assisted assembly of fluid flow, meniscus, pressure, template, electromagnetic field, contact and strain, and analyzes the characteristics of these techniques. Moreover, by briefly enumerating the applications of aligned NW films in solar cells, organic light-emitting diodes, and touch screens, the superiority of aligned NW films over random NW films is also addressed. Results: Contact-assisted assembly exhibits the best arrangement effect, reaching a 98.6% alignment degree within ±1°. Under the same conditions, shorter NWs show better alignment in several cases. The combination of various assembly techniques is also an effective means to improve the alignment effect. Conclusion: There is still room for improvement in the precise control of NW position, density, and orientation in a simple, efficient and compatible process. Therefore, follow-up research work is needed to conquer these problems. Moreover, a process that can realize NWs’ alignment and film patterning simultaneously is also a desirable scheme for fabricating personalized devices.