Fabrication of highly reproducible polymer solar cells using ultrasonic substrate vibration posttreatment

Abstract

"Fabrication of highly reproducible polymer solar cells using ultrasonic substrate vibration posttreatment," J. Photon. Energy 6(4), 045502 (2016), doi: 10.1117/1.JPE.6.045502. Abstract. Organic solar cells are usually nonreproducible due to the presence of defects in the structure of their constituting thin films. To minimize the density of pinholes and defects in PEDOT:PSS, which is the hole transporting layer of a standard polymer solar cell, i.e., glass/ ITO/PEDOT:PSS/P3HT:PCBM/Al, and to reduce scattering in device performance, wet spun-on PEDOT:PSS films are subjected to imposed ultrasonic substrate vibration posttreatment (SVPT). The imposed vibration improves the mixing and homogeneity of the wet spun-on films, and consequently the nanostructure of the ensuing thin solid films. For instance, our results show that by using the SVPT, which is a mechanical, single-step and low-cost process, the average power conversion efficiency of 14 identical cells increases by 25% and the standard deviation decreases by 22% indicating that the device photovoltaic performance becomes more consistent and significantly improved. This eliminates several tedious and expensive chemical and thermal treatments currently performed to improve the cell reproducibility. © The Authors.Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

Tailoring Characteristics of PEDOT:PSS Coated on Glass and Plastics by Ultrasonic Substrate Vibration Post Treatment

“…Although the aforementioned chemical methods can improve the conductivity of PEDOT:PSS films, a facile, low-cost, and environmentally friendly mechanical technique is more appealing. In this context, Eslamian and coworkers [40][41][42][43][44] demonstrated remarkable improvement in almost all characteristics of PEDOT:PSS thin films by imposing ultrasonic vibration on the substrate and the wet film during or after the deposition process by spin or spray coating. In the case of spray-on PEDOT:PSS films [40] and PEDOT:PSS/graphene composite films [45,46], it was observed that employing ultrasonic vibration promotes solution mixing and film surface levelling, due to a mild instability caused by the vibration [45,46], resulting in a more uniform and conductive PEDOT:PSS thin film.…”

“…Eslamian [47] also reviewed conventional and emerging applications of ultrasonic vibration in various configurations and systems. The aforementioned works [40][41][42][43][44] were performed with a single frequency of 40 kHz on films coated on glass substrates. Owing to the potential of the method, in this work, we carefully characterized the response of the ultrasonic transducers and systematically investigated the effect of varying ultrasonic vibration frequency and power on characteristics of spun PEDOT:PSS thin films, to gain further insight and also obtain optimum conditions from a practical point of view.…”

Facile and low-cost mechanical techniques for the fabrication of solution-processed polymer and perovskite thin film transistors

“…Another important topic in emerging FETs is the stability of the solution-processed layers and the device hysteresis when subjected to a pulsed gate voltage over multiple cycles [11]. While the topic was not studied in this work, in [2] and [42] we have demonstrated that the application of the ultrasonic vibration on the active layers has a remarkable effect on the stability of the films used in polymer and perovskite solar cells, respectively.…”

“…Poly(3-hexylthiophene) (P3HT) and methylammonium lead iodide (CH 3 NH 3 PbI 3 ) perovskite are employed as the solution-processed semiconducting channels. P3HT has been used extensively in organic photovoltaics (OPV) [2] and OFETs [1,[3][4][5][6][7][8]. Perovskites, which have been extensively used in perovskite solar cells [9,10], have been recently employed in the area of thin film FETs to develop high performance devices.…”

Excitation of Wet Perovskite Films by Ultrasonic Vibration Improves the Device Performance

“…Therefore, in this study, a novel, facile, low-cost, and more repeatable mechanical approach, termed as ultrasonic substrate vibration post treatment (SVPT), is employed to control the crystal growth and to improve the interfacial contacts between the perovskite and m-TiO 2 layers. The application of the SVPT method on organic [20,21] and perovskite [22] solar cells has shown that imposing low-amplitude ultrasonic vibration on the wet thin films results in an improvement in the film nanostructure and the device reproducibility, because it promotes the evaporation rate [23] and causes micromixing of the solution components [24,25]. However, in the aforementioned studies, the effect of the imposed vibration on the crystallization of the perovskite precursor solutions deposited on a mesoporous layer, such m-TiO 2 layer, has not been investigated.…”