Interface Modification for Energy Level Alignment and Charge Extraction in CsPbI3 Perovskite Solar Cells

Zafar Iqbal; Fengshuo Zu; Artem Musiienko; Emilio Gutierrez-Partida; Hans Köbler; Thomas W Gries; Gennaro V Sannino; Laura Canil; Norbert Koch; Martin Stolterfoht; Dieter Neher; Michele Pavone; Ana Belen Muñoz-García; Antonio Abate; Qiong Wang

doi:10.1021/acsenergylett.3c01522

Interface Modification for Energy Level Alignment and Charge Extraction in CsPbI₃ Perovskite Solar Cells

ACS Energy Lett. 2023 Sep 22;8(10):4304-4314. doi: 10.1021/acsenergylett.3c01522. eCollection 2023 Oct 13.

Authors

Zafar Iqbal¹, Fengshuo Zu², Artem Musiienko¹, Emilio Gutierrez-Partida³, Hans Köbler¹, Thomas W Gries¹, Gennaro V Sannino^{1

4}, Laura Canil¹, Norbert Koch^{1

2}, Martin Stolterfoht^{3

5}, Dieter Neher³, Michele Pavone⁶, Ana Belen Muñoz-García⁴, Antonio Abate^{1

7

8}, Qiong Wang¹

Affiliations

¹ Helmholtz-Zentrum Berlin für Materialien und Energie GmbH. Hahn-Meitner-Platz 1, 14109 Berlin, Germany.
² Institut für Physik & IRIS Adlershof, Humboldt-Universität zu Berlin, 12489 Berlin, Germany.
³ Institute for Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Straße 24-25, 14476 Potsdam-Golm, Germany.
⁴ Department of Physics "Ettore Pancini", University of Naples Federico II, Comp. Univ. Monte S. Angelo, via Cintia 26, 80126 Naples, Italy.
⁵ The Chinese University of Hong Kong, Electronic Engineering Department, Shatin N.T., Hong Kong 999077, People's Republic of China.
⁶ Department of Chemical Sciences, University of Naples Federico II, Comp. Univ. Monte S. Angelo, Via Cintia 26, 80126 Naples, Italy.
⁷ Department of Chemistry, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany.
⁸ Department of Chemical Materials and Production Engineering, University of Naples Federico II, Piazzale Vincenzo Tecchio 80, 80125 Naples, Italy.

Abstract

In perovskite solar cells (PSCs) energy level alignment and charge extraction at the interfaces are the essential factors directly affecting the device performance. In this work, we present a modified interface between all-inorganic CsPbI₃ perovskite and its hole-selective contact (spiro-OMeTAD), realized by the dipole molecule trioctylphosphine oxide (TOPO), to align the energy levels. On a passivated perovskite film, with n-octylammonium iodide (OAI), we created an upward surface band-bending at the interface by TOPO treatment. This improved interface by the dipole molecule induces a better energy level alignment and enhances the charge extraction of holes from the perovskite layer to the hole transport material. Consequently, a V_oc of 1.2 V and a high-power conversion efficiency (PCE) of over 19% were achieved for inorganic CsPbI₃ perovskite solar cells. Further, to demonstrate the effect of the TOPO dipole molecule, we present a layer-by-layer charge extraction study by a transient surface photovoltage (trSPV) technique accomplished by a charge transport simulation.