Slow recombination in quantum dot solid solar cellusing p–i–n architecture with organic p-type holetransport material

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Vol. 3; no. 41; p. 20579
• Main Authors: Zhang, Xiaoliang, Justo, Yolanda, Maes, Jorick, Walravens, Willem, Zhang, Jindan, Liu, Jianhua, Hens, Zeger, Johansson, Erik M. J.
• Format: Journal Article
• Language: English
• Published: 2015
• ISSN: 2050-7488
• DOI: 10.1039/c5ta07111a

The interfaces between different materials in the heterojunction colloidal quantum dot (QD) solar cell playan important role for charge carrier separation, recombination and collection. Here, an organic–inorganichybrid p–i–n architecture for the heterojunction PbS QD solid solar cell is constructed to increase thecharge extraction and reduce charge recombination. Heavily doped poly(3-hexylthiophene-2,5-diyl)(P3HT) is applied as hole transport interlayer between the QD film and metal contact electrode. Theresults show that the P3HT interlayer diminishes the charge carrier recombination at the QD film/metalcontact electrode interface leading to increased open-circuit voltage and increased electron life time.Furthermore, after incorporation of P3HT interlayer an additional p–i heterojunction might form atP3HT/QD film interface resulting in increased depletion region, which promotes charge carrierextraction under working conditions. Two other organic p-type interlayers are also investigated,however, the results indicate that a barrier for charge extraction is formed for these devices, which isexplained by the difference in energy levels. The solar cell with the P3HT interlayer exhibits a powerconversion efficiency of 5.1% at 1 sun of illumination and ambient atmosphere, which is 20% highercompared to the solar cell without any hole transport interlayer.