Enhancing the performances of P3HT:PCBM – MoS3 based H2-evolving photocathodes with interfacial layers

Tiphaine Bourgeteau (1) , Denis Tondelier (2) , Bernard Geffroy (1) , Romain Brisse (1) , Renaud Cornut (1) , Vincent Artero (3) , Bruno Jousselme (1)

1 LICSEN UMR 3685 - Laboratoire Innovation en Chimie des Surfaces et NanoSciences
2 LPICM - Laboratoire de physique des interfaces et des couches minces [Palaiseau]
3 LCBM - UMR 5249 - Laboratoire de Chimie et Biologie des Métaux

Organic semiconductors have great potential for producing hydrogen in a durable and economically viable manner, as they rely on readily available materials and can be solution-processed over large areas. With the objective of building efficient hybrid organic-inorganic photo-electrochemical cells, we combined a noble metal-free and solution-processable catalyst for proton reduction, MoS3, and a poly-(3-hexylthiophene):phenyl-C61-butyric acid methyl ester (P3HT:PCBM) bulk heterojunction (BHJ). Different interfacial layers were investigated to improve the charge transfer between P3HT:PCBM and MoS3. Metallic Al\Ti interfacial layers led to an increase of the photocurrent up to 8 mA cm?2 at reversible hydrogen electrode (RHE) potential with a 0.6 V anodic shift of the HER onset potential, a value close to the open circuit potential of the P3HT:PCBM solar cell. A 50 nm thick C60 layer also works as interfacial layer, with current density reaching 1 mA cm?2 at RHE potential. Moreover, two recently highlighted figures-of-merit, measuring the ratio of power saved, Φsaved,ideal and Φsaved,NPAC, were evaluated and discussed to compare the performances of various photocathodes assessed in a three-electrode configuration. Φsaved,ideal and Φsaved,NPAC use the RHE and a non-photoactive electrode with identical catalyst as dark electrode, respectively. They provide different information especially for the differentiation of the role of the photogenerating layer and the role of the catalyst. Best results were obtained with the Al\Ti metallic interlayer, with Φsaved,ideal and Φsaved,NPAC reaching 0.64 % and 2.05 % respectively.

Domaines: Chimie

Tiphaine Bourgeteau, Denis Tondelier, Bernard Geffroy, Romain Brisse, Renaud Cornut, et al.. Enhancing the performances of P3HT:PCBM – MoS3 based H2-evolving photocathodes with interfacial layers. ACS Applied Materials & Interfaces, 2015, 7, pp.16395-16403. ⟨10.1021/acsami.5b03532⟩. ⟨hal-01187809⟩