Enhanced Grain Size, Photoluminescence, and Photoconversion Efficiency with Cadmium Addition during the Two-Step Growth of CH3NH3PbI3

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• 作者：Suneth C. WatthageZhaoning Song ; Niraj ShresthaAdam B. Phillips ; Geethika K. Liyanage ; Paul J. Roland ; Randy J. Ellingson ; Michael J. Heben
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2017
• 出版时间：January 25, 2017
• 年：2017
• 卷：9
• 期：3
• 页码：2334-2341
• 全文大小：441K
• ISSN：1944-8252

文摘

Control over grain size and crystallinity is important for preparation of methylammonium lead iodide (MAPbI₃) solar cells. We explore the effects of using small concentrations of Cd²⁺ and unusually high concentrations of methylammonium iodide during the growth of MAPbI₃ in the two-step solution process. In addition to improved crystallinity and an enhancement in the size of the grains, time-resolved photoluminescence measurements indicated a dramatic increase in the carrier lifetime. As a result, devices constructed with the Cd-modified perovskites showed nearly a factor of 2 improvement in the power conversion efficiency (PCE) relative to similar devices prepared without Cd addition. The grains also showed a higher degree of orientation in the ⟨110⟩ direction, indicating a change in the growth mechanism, and the films were compact and smooth. We propose a Cd-modified film growth mechanism that invokes a critical role for low-dimensional Cd perovskites to explain the experimental observations.