Roll-to-Roll Processing of Inverted Polymer Solar Cells using Hydrated Vanadium(V)Oxide as a PEDOT:PSS Replacement

Nieves Espinosa,David M Tanenbaum,Jens W Andreasen,Mikkel Jørgensen,Frederik C Krebs,Henrik Friis Dam

doi:10.3390/ma4010169

Nieves Espinosa, David M Tanenbaum + Show 4 more

Open Access

https://doi.org/10.3390/ma4010169

Copy DOI

Abstract

The use of hydrated vanadium(V)oxide as a replacement of the commonly employed hole transporting material PEDOT:PSS was explored in this work. Polymer solar cells were prepared by spin coating on glass. Polymer solar cells and modules comprising 16 serially connected cells were prepared using full roll-to-roll (R2R) processing of all layers. The devices were prepared on flexible polyethyleneterphthalate (PET) and had the structure PET/ITO/ZnO/P3HT:PCBM/V2O5·(H2O)n/Ag. The ITO and silver electrodes were processed and patterned by use of screen printing. The zinc oxide, P3HT:PCBM and vanadium(V)oxide layers were processed by slot-die coating. The hydrated vanadium(V)oxide layer was slot-die coated using an isopropanol solution of vanadyl-triisopropoxide (VTIP). Coating experiments were carried out to establish the critical thickness of the hydrated vanadium(V)oxide layer by varying the concentration of the VTIP precursor over two orders of magnitude. Hydrated vanadium(V)oxide layers were characterized by profilometry, scanning electron microscopy, energy dispersive X-ray spectroscopy, and grazing incidence wide angle X-ray scattering. The power conversion efficiency (PCE) for completed modules was up to 0.18%, in contrast to single cells where efficiencies of 0.4% were achieved. Stability tests under indoor and outdoor conditions were accomplished over three weeks on a solar tracker.

Highlights

Polymer solar cells [1,2,3] have seen remarkable progress in recent years and have developed from being a scientific curiosity to an emerging technology that can be manufactured industrially [4,5,6,7,8] and demonstrated in real applications [9,10,11,12,13]
We evaluate hydrated vanadium(V)oxide as a PEDOT:PSS replacement for polymer solar cells prepared under industrially relevant conditions
Hydrated vanadium(V)oxide has been employed in the fabrication of inverted PEDOT:PSS free polymer solar cells compatible with all solution processing of all layers

Summary

Introduction

Polymer solar cells [1,2,3] have seen remarkable progress in recent years and have developed from being a scientific curiosity to an emerging technology that can be manufactured industrially [4,5,6,7,8] and demonstrated in real applications [9,10,11,12,13]. The two outer layers are highly conducting electrodes for extraction of the generated electrical current. The electron selective layers have been developed recently but have otherwise been limited to the intentional use of low work function metals alone or in combination with very thin wide band gap insulators such as LiF and MgF2. The hole selective layer has been limited almost exclusively to various formulations of PEDOT:PSS. The reasons for this are mostly historical and PEDOT:PSS was first employed as an intermediate layer that served to stabilize the work function of ITO and to planarize it, enabling formation of nearly defect free thin films on top [17]. PEDOT:PSS is highly stable photochemically and is stable towards oxidative conditions

Methods

Results

Conclusion