Energy level diagram of HC(NH2)2PbI3 single crystal evaluated by electrical and optical analyses

• DOI: 10.1039/c7cp07477h
• Publication Date: 2017-12-22T11:21:48Z
• Authors: Takeyuki Sekimoto; Michio Suzuka; Tomoyasu Yokoyama; Ryusuke Uchida; Shin’ichi Machida; Takashi Sekiguchi; Kenji Kawano
• Keywords: Formamidinium; Crystal (programming language); Band diagram

Recently, organic-inorganic halide perovskites have received attention for applications in solar cells. Measurements of high-quality single crystals reveal lower defect densities and longer carrier lifetimes than those conventional thin films, which result improved electrical optical properties. However, crystal surfaces are sensitive to exposure ambient conditions, degrade under long-term storage air. The surface also shows differences from the bulk terms its electronic characteristics. For a heterojunction device, interface at is important. Understanding difference between properties offers insights into device design. Here, we prepared non-sliced sliced formamidinium lead iodide (FAPbI3; FA+ = HC(NH2)2+) with bandgap 1.4 eV, matches well requirements cell photoabsorption layers. We evaluate energy level diagrams regions, respectively. Our data indicate that valence band maximum region higher region. discuss hypotheses well-known unexplained phenomena (multiple bandgaps narrowing) seen absorption photoluminescence spectra crystals. conclude these effects likely caused by combination degraded surface, Rashba-splitting bulk, self-absorption itself.