Novel Diffusion-Regulated Layering Methodology to Improve Blend Miscibility and Thermal Stability of Organic Photovoltaics

Chihyung Lee, Hyeon Yeong Jo, Minwoo Nam, Janghee Hong, Gyu Hee Kim, Hyun Hwi Lee, Jehan Kim, Rakwoo Chang, Doo Hyun Ko

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Extensive research on bulk-heterojunction (BHJ) optimization has advanced organic photovoltaics (OPVs). However, the need for research addressing the issue of morphological instability and ensuring long-term durability remains a priority. Herein, a diffusion-governed morphological modification methodology via a sequential deposition (SD) process comprising ternary components with low miscibility is demonstrated. Sequential coating of a high glass transition temperature (Tg) material and a host binary blend induces a concentration difference between successively coated layers, allowing for effective blending of immiscible materials during solvent evaporation. The enhanced miscibility of the SD-processed BHJ layer facilitates molecular interactions between the high Tg material and the host materials, thereby increasing the Tg of the BHJ blend. The SD-processed OPVs exhibit superior photovoltaic performance and suppressed glass transition under thermal stress compared to reference OPVs fabricated via a conventional method. After 500 h of thermal aging at 85 °C, the SD-BHJ OPV retains over 80% of its initial efficiency, whereas the reference device shows a drastic drop to below 80% of its initial efficiency after only 80 h. This study provides a step toward efficient, long-term stable OPVs by overcoming the limitations of blend miscibility and poor thermal durability of conventional BHJ systems via a SD process.

Original languageEnglish
Article number2308047
JournalAdvanced Functional Materials
Volume34
Issue number2
DOIs
StatePublished - 9 Jan 2024

Keywords

  • glass transition temperature
  • miscibility
  • morphological stability
  • organic photovoltaics
  • sequential deposition

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