It Takes Two to Tango—Double-Layer Selective Contacts in Perovskite Solar Cells for Improved Device Performance and Reduced Hysteresis

• DOI: 10.1021/acsami.7b00900
• Publication Date: 2017-04-24T09:42:16Z
• Authors: Lukas Kegelmann; Christian M. Wolff; Celline Awino; Felix Lang; Eva L. Unger; Lars Korte; Thomas Dittrich; Dieter Neher; Bernd Rech; Steve Albrecht
• Keywords: Photocurrent; Hysteresis; Perovskite solar cell; Photoactive layer

Solar cells made from inorganic–organic perovskites have gradually approached market requirements as their efficiency and stability improved tremendously in recent years. Planar low-temperature processed perovskite solar are advantageous for possible large-scale production but more prone to exhibiting photocurrent hysteresis, especially the regular n–i–p structure. Here, a systematic characterization of different electron selective contacts with variety chemical electrical properties planar devices below 180 °C is presented. The inorganic metal oxides TiO2 SnO2, organic fullerene derivatives C60, PCBM, ICMA, well double-layers oxide/PCBM structure used transport materials (ETMs). Perovskite layers deposited atop ETMs herein applied fabrication method show similar morphology according scanning microscopy. Further, surface photovoltage spectroscopy measurements indicate comparable absorber qualities on all ETMs, except TiO2, which shows prominent influence defect states. Transient photoluminescence studies together current–voltage scans over broad range scan speeds reveal faster charge extraction, less pronounced hysteresis effects, higher efficiencies compared those oxide ETMs. Beyond this, only double-layer ETM structures substantially diminish effects performed strongly enhance power conversion up champion stabilized value 18.0%. results reduced recombination losses TiO2/PCBM contact design: First, reduction shunt paths through ITO layer. Second, an hole blocking by wide band gap oxide. Third, decreased due energetically favorable contact, implied photoelectron measurements. demonstrated improvements multilayer may serve general design guideline cells.