High charge carrier mobilities and lifetimes in organolead trihalide perovskites.

Journal article

Organic-inorganic lead-halide perovskites have recently drawn great attention as novel absorbers and charge transporters in low-cost solar cells. It is still largely unknown what makes these materials so phenomenally well-suited for charge generation and conduction. Here we show that both CH3NH3PbI3 and CH3NH3PbI3−xClx exhibit exceptionally low mono-molecular and bi-molecular charge-carrier decay rates, defying the Langevin limit by at least 4 orders of magnitude. Using transient THz spectroscopy, we establish lower bounds for the high-frequency charge mobility of 11.6 cm 2/Vs for CH3NH3PbI3−xClx and 8cm2/Vs for CH3NH3PbI3, which are remarkably high for solution-processed materials. We deduce charge-carrier diffusion lengths as a function of charge density and find values exceeding a few microns for CH3NH3PbI3−xClx, under typical device operating conditions. For CH3NH3PbI3, diffusion lengths are a factor∼4 lower because of higher mono- and bi-molecular recombination rates. These findings underline the suitability of this material class for planarheterojunction device structures and highlight the potential for performance tuning through manipulation of the polar metal-halide bond.

Authors: Wehrenfennig, C; Eperon, G; Johnston, M; Snaith, H; Herz, L

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Wiley
• Journal: Advanced Materials
• Volume: 26
• Issue: 10
• Pages: 1584-1589
• Publication date: 2014-03-01
• DOI: 10.1002/adma.201305172
• EISSN: 1521-4095
• ISSN: 0935-9648
• Language: English
• Keywords: Iodide; Recombination; Methylammonium; PL; Charge transport; Halide; CH3NH3PbI; Solar; Lead; Terahertz; Chloride; Mobility; Organometal; Photoluminescence; Photovoltaics; Perovskite; THz