Highly conductive and stable graphene/PEDOT:PSS composite as a metal free cathode for organic dye-sensitized solar cells

Jae Cheon Kim, Md Mahbubur Rahman, Myung Jong Ju, Jae Joon Lee

Research output: Contribution to journalArticlepeer-review

23 Scopus citations

Abstract

Platinum (Pt) as the counter electrode (CE) in dye-sensitized solar cells (DSSCs) is expensive and non-optimal for cobalt(ii/iii) redox couples, which can tune and improve the performance of DSSCs, thus motivating the search for replacements of the Pt CE. Graphene nanoplatelets (GnPs) are possible alternatives to Pt CEs but they are mechanically unstable as CEs due to their poor substrate adhesion. Here we report a new type of PEDOT:PSS (PP)/GnP (PPG) composite that maintains the catalytic performance of GnPs with enhanced adhesion to the substrate via a conductive PEDOT matrix. The resultant PPG exhibited extremely low charge-transfer resistance (Rct) compared to Pt in its role as an electrocatalyst toward a Co(bpy)32+/3+ (bpy = 2,2′-bipyridine) redox couple, and displayed extremely high electrochemical stability for Co(bpy)33+ reduction even after 1000 cycles. The inter-stacking of GnP layers between PEDOT and PSS was confirmed by XPS and Raman spectra. It helps to delocalize charges in the PEDOT backbone and rapidly transfers electrons from the external circuit to Co(bpy)33+. This reduces the Rct and ultimately improves the photovoltaic performance. The DSSC based on Y123 sensitizer and PPG-CE showed a higher photovoltaic performance of 8.33% than its Pt counterpart does (7.99%) under the optimized conditions.

Original languageEnglish
Pages (from-to)19058-19066
Number of pages9
JournalRSC Advances
Volume8
Issue number34
DOIs
StatePublished - 2018

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