Effects of 5-Ammonium Valeric Acid Iodide as Additive on Methyl Ammonium Lead Iodide Perovskite Solar Cells

Abstract

During the past decade, the power conversion efficiency (PCE) of perovskite solar cells (PSCs) has risen rapidly, and it now approaches the record for single crystal silicon solar cells. However, these devices still suffer from a problem of stability. To improve PSC stability, two approaches have been notably developed: the use of additives and/or post-treatments that can strengthen perovskite structures and the use of a nontypical architecture where three mesoporous layers, including a porous carbon backcontact without hole transporting layer, are employed. This paper focuses on 5-ammonium valeric acid iodide (5-AVAI or AVA) as an additive in methylammonium lead iodide (MAPI). By combining scanning electron microscopy (SEM), X-ray diffraction (XRD), time-resolved photoluminescence (TRPL), current–voltage measurements, ideality factor determination, and in-depth electrical impedance spectroscopy (EIS) investigations on various layers stacks structures, we discriminated the effects of a mesoscopic scaffold and an AVA additive. The AVA additive was found to decrease the bulk defects in perovskite (PVK) and boost the PVK resistance to moisture. The triple mesoporous structure was detrimental for the defects, but it improved the stability against humidity. On standard architecture, the PCE is 16.9% with the AVA additive instead of 18.1% for the control. A high stability of TiO2/ZrO2/carbon/perovskite cells was found due to both AVA and the protection by the all-inorganic scaffold. These cells achieved a PCE of 14.4% in the present work.

Halogen Bond Involved Post‐Treatment for Improved Performance of Printable Hole‐Conductor‐Free Mesoscopic Perovskite Solar Cells

“…[ 24 ] Three lifetimes of τ 1 , τ 2 , and τ 3 could be assigned to electron extraction, interface recombination, and bulk recombination, respectively. [ 25 ] We found that the introduction of BFN rarely changed the carrier lifetimes, especially the electron extraction lifetime τ 1 . The reason may be that BFN just located in a thin layer of perovskite near carbon electrode, which hardly influenced PL properties at the TiO 2 side.…”

GABr Post-Treatment for High-Performance MAPbI3 Solar Cells on Rigid Glass and Flexible Substrate

“…x GABr denotes x mg·ml −1 GABr treatment in this work unless otherwise noted. The diffraction peaks at 14.08°, 28.42° and 31.88° corresponding to the (110), (220), and (330) planes of MAPbI 3 , and the peak at 12.78° is assigned to PbI 2 , which disappears after GABr treatment [ 37 , 38 ]. The intensity of MAPbI 3 peaks gradually increases at low concentrations of GABr, whereas when x is higher than 5, the intensity decreases.…”

Heterojunction In Situ Constructed by a Novel Amino Acid-Based Organic Spacer for Efficient and Stable Perovskite Solar Cells

“…The photovoltaic properties of the resultant low-dimensional perovskites are greatly affected by the chemistry of the additive molecules, which then offer great potential for the preparation of perovskite materials with customized characteristics. Among the above-mentioned large cations, 5-AVA + has been employed as an excellent dopant to tailor the crystal structure of the absorber layer, resulting in an improved charge carrier lifetime . For example, Mei et al showed that the MAPbI 3 crystals were strengthened by 5-AVA + at the grain boundaries, and they indicated that the decomposition and ionic migration could be inhibited, meeting stability standards of IEC61215:2016 qualification tests for 9000 h .…”