Electron and hole transfer at metal oxide/Sb sub(2)S sub(3)/s piro-OMeTAD heterojunctions

• Published in: Energy & environmental science Vol. 5; no. 12; pp. 9760 - 9764
• Main Authors: O'Mahony, Flannan TF, Lutz, Thierry, Guijarro, Nestor, Gomez, Roberto, Haque, Saif A
• Format: Journal Article
• Language: English
• Published: 01.11.2012
• ISSN: 1754-5692; 1754-5706
• DOI: 10.1039/c2ee23037b

Antimony sulfide has recently demonstrated huge potential as an absorber material in solid-state semiconductor-sensitised solar cells (SSSCs). Here, we present a transient absorption spectroscopy study of the TiO sub(2)/Sb sub(2)S sub(3 )/spiro-OMeTAD heterojunctions to elucidate the key factors influencing charge photogeneration. Efficient device performance requires that photoresponse extends into the near-infrared, yet we find that the efficiency of charge separation at the TiO sub(2)/Sb sub(2)S sub(3 ) interface decreases significantly as increasingly red-absorbing Sb sub(2)S sub(3) nanocrystals are photoexcited. However, the efficiency of hole transfer to spiro-OMeTAD appears much less sensitive to shifts in the Sb sub(2)S sub(3) absorption edge and we also observe hole transfer to spiro-OMeTAD occurring on ZrO sub(2) substrates, where electron injection does not occur. These observations may point to the importance of the hole transfer reaction not simply as a means of regenerating the sensitiser, but rather as an integral part of the charge separation process in Sb sub(2)S sub(3) SSSCs. The present findings should help inform strategies aimed at further increasing the efficiency of nanocrystal sensitized solar cells.