Formamidine disulfide oxidant as a localised electron scavenger for >20% perovskite solar cell modules

Jun Zhu, Seulyoung Park, Oh Yeong Gong, Chang Hwun Sohn, Zijia Li, Zhenru Zhang, Bonghyun Jo, Wooyul Kim, Gill Sang Han, Dong Hoe Kim, Tae Kyu Ahn, Jaichan Lee, Hyun Suk Jung

Research output: Contribution to journalArticlepeer-review

65 Citations (Scopus)


Formamidinium lead iodide (FAPbI3)-based perovskites possess high light absorption and long diffusion lengths, making them strong candidates for highly efficient solar cells. However, despite these properties, primary intrinsic defects in FAPbI3 (i.e. iodine vacancy) induce strong electron localisation and become deep traps and recombination centres upon photoexcitation. Consequently, the carrier lifetime is significantly reduced and the superior properties are not fully utilised. Therefore, the manipulation of intrinsic defects has become a critical issue for realising highly efficient solar cells. Herein, formamidine disulfide dihydrochloride (FASCl) is used because the FAS2+ ion is a strong oxidant or electron scavenger. Substitution of the FAS2+ ion for the FA+ ion makes the iodine vacancy lose the strongly localised electrons and removes the deep traps. The incorporation of FASCl induces the formation of intermediate phases with a perovskite precursor, which can effectively stabilise the black α-phase FAPbI3 and retard the crystallisation rate, leading to compact full-coverage perovskite layers with high crystallinity and a large grain size. As a result, the optimal unit device (0.14 cm2) exhibits a remarkable power conversion efficiency (PCE) of 23.11%, a stabilised power output (SPO) of 22.83%, a low voltage deficit of 0.343 V, and a notable fill factor of 83.4%. Without encapsulation, the device retains ∼92.5% and ∼91.7% of its initial efficiency after 1000 h of either heating at 85 °C (thermal) or 50% relative humidity atmospheric testing, respectively. Moreover, the perovskite solar modules (PSMs) achieve PCE values of 20.75% (with a notable fill factor of 78.5%) and 17.44% for the active areas of 23.27 and 59.33 cm2, respectively.

Original languageEnglish
Pages (from-to)4903-4914
Number of pages12
JournalEnergy and Environmental Science
Issue number9
Publication statusPublished - 2021 Sept
Externally publishedYes

Bibliographical note

Funding Information:
This work was supported by the Basic Science Research Program through the National Research Foundation of Korea (No. 2019R1A2C2002661), the Institute of Information & Communications Technology Planning & Evaluation (IITP) grant funded by the Korean government (MSIT) (No. 2020-0-00541, Flexible Photovoltaic Device Module with Autonomous Power Supply for Smart Farm Wireless Composite IoT Sensor), Creative Materials Discovery Program through the National Research Foundation of Korea (NRF-2019M3D1A1078296 and NRF-2019M3D1A2104108) funded by the Ministry of Science and ICT, and the Basic Research Lab Program (2020R1A4A2002161) through the National Research Foundation of Korea. Computational resources were supported by KISTI supercomputing center (KSC-2020-CRE-0028).

Publisher Copyright:
© The Royal Society of Chemistry.

ASJC Scopus subject areas

  • Environmental Chemistry
  • Renewable Energy, Sustainability and the Environment
  • Nuclear Energy and Engineering
  • Pollution


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