Bulk Incorporation of Molecular Dopants into Ruddlesden–Popper Organic Metal–Halide Perovskites for Charge Transfer Doping

유기 금속 할라이드 페로브스카이트는 우수한 광전기적 특성으로 반도체 재료로서 많은 관심을 받고 있다. 본 연구에서는 2차원 페로브스카이트 물질에 '매직 블루(magic blue)'라고 불리는 분자 물질을 효과적으로 전이하는 방법으로 immersion 도핑 방식을 제안하였으며, 용매 분자가 유기 스페이서 층 내 도핑 물질의 대량 확산을 용이하게 한다는 메커니즘을 제안하였다. 또한 쉽게 이용이 가능한 다섯 가지 용매물질을 연구하여 효과적인 도핑 방법에 활용가능한 용매의 물리 화학적 기준도 제시하였다. 본 연구는 2차원 페로브스카이트 물질의 전기적 특성을 제어하기 위한 방향을 제시하고, 페로브스카이트 전자 및 광전자 기기용 소자 성능의 향상에 기여할 것으로 기대된다.

Organic metal-halide perovskites (OHPs) have recently attracted much attention as next-generation semiconducting materials due to their outstanding opto-electrical properties. However, OHPs currently suffer from the lack of efficient doping methods, while the traditional method of atomistic doping having clear limitations in the achievable doping range. While doping with molecular dopants, a family of versatile dopants with rooms for molecular design, has been suggested as a solution to this problem, the action of these dopants was typically restricted to perovskite surfaces, therefore significantly reducing their doping potential. In this study, we report successful bulk inclusion of ‘magic blue’, a molecular dopant, into two-dimensional (2D) Ruddlesden–Popper perovskites. Our doping strategy of immersing the perovskite film in dopant solution increased the electrical current up to ~60 times while maintaining clean film surface. We provide a full mechanistic picture of such immersion doping, in which the solvent molecule facilitates bulk diffusion of dopant molecule inside the organic spacer layer. Physical criteria for judicious choice of solvents in immersion doping is developed based on readily available solvent properties. The immersion doping method developed in this work which enables bulk molecular doping in OHPs will provide a strategic doping methodology for controlling electrical properties of OHPs for electronic and optoelectronic devices.

Authors : Jonghoon Lee^†, Kyeong-Yoon Baek^†, Jeongjae Lee^†, Heebeom Ahn, Yongjin Kim, Hyungbin Lim, Yeeun Kim, Jaeyong Woo, Samuel D. Stranks, Sung Keun Lee, Henning Sirringhaus, Keehoon Kang* & Takhee Lee* 

DOI: 10.1002/adfm.202302048

Published online: 12 May 2023

Link: https://onlinelibrary.wiley.com/doi/10.1002/adfm.202302048