Synergistic Effect of N, N-Dimethylformamide and Hydrochloric Acid on the Growth of MAPbI3 Perovskite Films for Solar Cells

Hao Xiong; Giovanni DeLuca; Udo Bach; Linqin Jiang; Qinghong Zhang; Elsa Reichmanis; Yu Qiu

doi:10.1021/acsomega.0c04102

Synergistic Effect of N, N-Dimethylformamide and Hydrochloric Acid on the Growth of MAPbI₃ Perovskite Films for Solar Cells

ACS Omega. 2020 Dec 8;5(50):32295-32304. doi: 10.1021/acsomega.0c04102. eCollection 2020 Dec 22.

Authors

Hao Xiong^{1

2

3}, Giovanni DeLuca^{2

4

5

6}, Udo Bach⁶, Linqin Jiang¹, Qinghong Zhang³, Elsa Reichmanis^{2

4}, Yu Qiu¹

Affiliations

¹ Key Laboratory of Green Perovskites Application of Fujian Province Universities, Fujian Jiangxia University, Fuzhou 350108, China.
² School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, 311 Ferst Drive NW, Atlanta, Georgia 30332, United States.
³ State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai 201620, P. R. China.
⁴ School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive, Atlanta, Georgia 30332, United States.
⁵ CSIRO Manufacturing, Clayton, Victoria 3168, Australia.
⁶ Department of Chemical Engineering, Monash University, Clayton, Victoria 3800, Australia.

Abstract

Perovskite solar cells have emerged as a promising next-generation electrical power generating tool. However, imperfections in perovskite films are one of the crucial factors preventing the commercialization of perovskite solar cells. Passivation has proven to be an effective strategy to reduce the density of defect states in perovskite crystals and inhibit ion migration. Although significant work on chloride ion and N,N-dimethylformamide (DMF) has shown that the additives are able to passivate different types of trap defects, systematic studies on the effects of DMF and HCl on perovskite crystallization when used in conjunction with each other are elusive. Here, we systematically investigated the synergistic effect of DMF and hydrochloric acid (HCl) on methylammonium (MA⁺)-based perovskite films with the two-step spin-coating method. As a Lewis base, DMF coordinates well with Pb²⁺ to facilitate a decrease in the number of defects, thereby improving the carrier separation and transport, while HCl improves the overall perovskite film morphology. Addition of 20 μL HCl/20 μL DMF to 10 mL of methylammonium iodide/isopropyl alcohol solution afforded ca. 500 nm thick perovskite films with no observable defects within the grains. The process allowed fabrication of devices with an active area of 0.16 cm², which produced power conversion efficiencies up to 18.37% with minimal hysteresis.