Anomalous Charge-Extraction Behavior for Graphene-Oxide (GO) and Reduced Graphene-Oxide (rGO) Films as Efficient p-Contact Layers for High-Performance Perovskite Solar Cells

Efat Jokar, Zhong Yi Huang, Sudhakar Narra, Chi Yung Wang, Vidya Kattoor, Chih Chun Chung, Wei-Guang Diau*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

50 Scopus citations

Abstract

Reduced graphene oxides (rGO) are synthesized via reduction of GO with reducing agents as a hole-extraction layer for high-performance inverted planar heterojunction perovskite solar cells. The best efficiencies of power conversion (PCE) of these rGO cells exceed 16%, much greater than those made of GO and poly(3,4-ethenedioxythiophene):poly(styrenesulfonate) films. A flexible rGO device shows PCE 13.8% and maintains 70% of its initial performance over 150 bending cycles. It is found that the hole-extraction period is much smaller for the GO/methylammonium lead-iodide perovskite (PSK) film than for the other rGO/PSK films, which contradicts their device performances. Photoluminescence and transient photoelectric decays are measured and control experiments are performed to prove that the reduction of the oxygen-containing groups in GO significantly decreases the ability of hole extraction from PSK to rGO and also retards the charge recombination at the rGO/PSK interface. When the hole injection from PSK to GO occurs rapidly, hole propagation from GO to the indium-doped tin oxide (ITO) substrate becomes a bottleneck to overcome, which leads to a rapid charge recombination that decreases the performance of the GO device relative to the rGO device.

Original languageEnglish
Article number1701640
JournalAdvanced Energy Materials
Volume8
Issue number3
DOIs
StatePublished - 25 Jan 2018

Keywords

  • charge extraction
  • charge recombination
  • graphene oxides
  • perovskites
  • reduced graphene oxides

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