Long-range balanced electron- and hole-transport lengths in organic-inorganic CH3NH3PbI3

• Main Authors: Xing, Guichuan, Mathews, Nripan, Sun, Shuangyong, Lim, Swee Sien, Lam, Yeng Ming, Grätzel, Michael, Mhaisalkar, Subodh Gautam, Sum, Tze Chien
• Other Authors: School of Materials Science & Engineering
• Format: Article
• Language: English
• Published: 2013
• Subjects: DRNTU::Engineering::Materials; DRNTU::Science
• Online Access: https://hdl.handle.net/10356/105166; http://hdl.handle.net/10220/16761
• Institution: Nanyang Technological University

Low-temperature solution-processed photovoltaics suffer from low efficiencies because of poor exciton or electron-hole diffusion lengths (typically about 10 nanometers). Recent reports of highly efficient CH3NH3PbI3-based solar cells in a broad range of configurations raise a compelling case for understanding the fundamental photophysical mechanisms in these materials. By applying femtosecond transient optical spectroscopy to bilayers that interface this perovskite with either selective-electron or selective-hole extraction materials, we have uncovered concrete evidence of balanced long-range electron-hole diffusion lengths of at least 100 nanometers in solution-processed CH3NH3PbI3. The high photoconversion efficiencies of these systems stem from the comparable optical absorption length and charge-carrier diffusion lengths, transcending the traditional constraints of solution-processed semiconductors.