Elimination of the light soaking effect and performance enhancement in perovskite solar cells using a fullerene derivative

Shuyan Shao, Mustapha Abdu-Aguye, Li Qiu, Lai-Hung Lai, Jian Liu, Sampson Adjokatse, Fatemeh Jahani Bahnamiri, Machteld E. Kamminga, Gert ten Brink, Thomas T.M. Palstra, Bart J. Kooi, Jan C. Hummelen, Maria Antonietta Loi

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In this work, we investigate how electron extraction layers (EELs) with different dielectric constants affect the device performance and the light-soaking phenomenon in hybrid perovskite solar cells (HPSCs). Fulleropyrrolidine with a triethylene glycol monoethyl ether side chain (PTEG-1) having a dielectric constant of 5.9 is employed as an EEL in HPSCs. The commonly used fullerene derivative [60] PCBM, which has identical energy levels but a lower dielectric constant of 3.9, is used as a reference. The device using PTEG-1 as the EEL shows a negligible light soaking effect, with a power conversion efficiency (PCE) of 15.2% before light soaking and a minor increase to 15.7% after light soaking. In contrast, the device using [60] PCBM as the EEL shows severe light soaking, with the PCE improving from 3.8% to 11.7%. Photoluminescence spectroscopy and impedance spectroscopy measurements indicate that trap-assisted recombination at the interface between the hybrid perovskite and the EEL is the cause of the light soaking effect in HPSCs. The trap-assisted recombination is effectively suppressed at the perovskite/PTEG-1 interface, while severe trap assisted recombination takes place at the perovskite/[60] PCBM interface. We attributed these experimental findings to the fact that the higher dielectric constant of PTEG-1 helps to screen the recombination between the traps and free electrons. In addition, the electron donating side chains of PTEG-1 may also contribute to the passivation of the electron traps. As a consequence, the devices using PTEG-1 as the EEL display a considerable increase in the efficiency and a negligible light soaking effect.
Original languageEnglish
Pages (from-to)2444-2452
Number of pages9
JournalEnergy & environmental science
Issue number7
Publication statusPublished - 2016
Externally publishedYes


  • Organometal halide perovskites
  • Lead iodide
  • Transport
  • Efficient
  • Electron
  • Stability
  • Diffusion
  • Devices
  • Lengths


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