Anomalous photovoltaic effect in organic-inorganic hybrid perovskite solar cells

Yongbo Yuan; Tao Li; Qi Wang; Jie Xing; Alexei Gruverman; Jinsong Huang

doi:10.1126/sciadv.1602164

Anomalous photovoltaic effect in organic-inorganic hybrid perovskite solar cells

Sci Adv. 2017 Mar 17;3(3):e1602164. doi: 10.1126/sciadv.1602164. eCollection 2017 Mar.

Authors

Yongbo Yuan¹, Tao Li², Qi Wang³, Jie Xing³, Alexei Gruverman², Jinsong Huang³

Affiliations

¹ Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588-0656, USA.; Hunan Key Laboratory of Super Microstructure and Ultrafast Process, School of Physics and Electronics, Central South University, Changsha, Hunan 410083, P. R. China.
² Department of Physics and Astronomy, University of Nebraska-Lincoln, Lincoln, NE 68588-0299, USA.
³ Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588-0656, USA.

Abstract

Organic-inorganic hybrid perovskites (OIHPs) have been demonstrated to be highly successful photovoltaic materials yielding very-high-efficiency solar cells. We report the room temperature observation of an anomalous photovoltaic (APV) effect in lateral structure OIHP devices manifested by the device's open-circuit voltage (V_OC) that is much larger than the bandgap of OIHPs. The persistent V_OC is proportional to the electrode spacing, resembling that of ferroelectric photovoltaic devices. However, the APV effect in OIHP devices is not caused by ferroelectricity. The APV effect can be explained by the formation of tunneling junctions randomly dispersed in the polycrystalline films, which allows the accumulation of photovoltage at a macroscopic level. The formation of internal tunneling junctions as a result of ion migration is visualized with Kelvin probe force microscopy scanning. This observation points out a new avenue for the formation of large and continuously tunable V_OC without being limited by the materials' bandgap.

Keywords: Anomalous Photovoltaic Effect; Organic-Inorganic Hybrid Perovskite; perovskite; solar cells.