A newly developed lithium cobalt oxide super hydrophilic film for large area, thermally stable and highly efficient inverted perovskite solar cells

Chien Hung Chiang, Cheng Chiang Chen, Mohammad Khaja Nazeeruddin, Chun Guey Wu

Research output: Contribution to journalArticlepeer-review

21 Scopus citations

Abstract

A new inorganic hole transporting layer, a sputtering made LiCoO2 film, was developed and used in an inverted perovskite solar cell (PSC) and sub-module (PSM). The LiCoO2 film prepared by RF magnetron sputtering is composed of nano-sized particles and a superhydrophilic surface after treating it with UV-ozone, and therefore can be wetted evenly with a (MAI + PbI2)/(DMF + DMSO) precursor solution. By applying chlorobenzene as an anti-solvent, a very dense film with big perovskite grains was formed. After depositing the C60 electron transporting layer, BCP hole blocking layer and Ag electrode, the best perovskite solar cell achieves a power conversion efficiency (PCE) of 19% with negligible current hysteresis. The high-efficiency cell is stable up to 90 °C in the inert atmosphere without encapsulation, and the PCE only decreases by 2% when the cell was heated at 100 °C for 30 minutes. When the cell was heated at 100 °C for 5 days, the PCE decreases by only 40%; nevertheless, under the same heating conditions, the efficiency of the PSC based on the PEDOT:PSS HTL is lost totally. The superhydrophilic surface of LiCoO2 made the even wetting of the large surface area with the perovskite precursor solution possible. Therefore the perovskite solar sub-module with an active area of 25.2 cm2 (on a 10 cm × 10 cm substrate) can be fabricated to achieve a power conversion efficiency of 16% which was further verified to be 15%. The high-efficiency sub-module based on the LiCoO2 HTL also shows good thermal stability, and ca. 10% of the efficiency was lost by heating at 100 °C for 30 minutes. The development of new inorganic hole transporting layers for large area, thermally stable and highly efficient perovskite solar sub-modules closes the gap for their near-future market exploitation.

Original languageEnglish
Pages (from-to)13751-13760
Number of pages10
JournalJournal of Materials Chemistry A
Volume6
Issue number28
DOIs
StatePublished - 2018

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