Polyacrylonitrile‐Coordinated Perovskite Solar Cell with Open‐Circuit Voltage Exceeding 1.23 V

Abstract

In solution-processed organic-inorganic halide perovskite films, halide-anion related defects including halide vacancies and interstitial defects can easily form at the surfaces and grain boundaries. The uncoordinated lead cations produce defect levels within the band gap, and the excess iodides disturb the interfacial carrier transport. Thus these defects lead to severe nonradiative recombination, hysteresis, and large energy loss in the device. Herein, polyacrylonitrile (PAN) was introduced to passivate the uncoordinated lead cations in the perovskite films. The coordinating ability of cyano group was found to be stronger than that of the normally used carbonyl groups, and the strong coordination could reduce the I/Pb ratio at the film surface. With the PAN perovskite film, the device efficiency improved from 21.58 % to 23.71 % and the open-circuit voltage from 1.12 V to 1.23 V, the ion migration activation energy increased, and operational stability improved.

Ionic liquid engineering enabled in‐plane orientated 1D perovskite nanorods for efficient mixed‐dimensional perovskite photovoltaics

“…More interestingly, the resonance peak of C≡N groups in CPMIMCl also shifts from 119.7 to 119.6 ppm, indicating strong interaction between C≡N groups with PbI 2 . The availability of C≡N groups further enhances the coordination ability of ILs with uncoordinated Pb 2+ , 21,25,26 which matches the results of ESP distribution maps and DFT calculation. We further investigate the binding energies of the element of control and CPMIMCl‐perovskite films using x‐ray photoelectron spectroscopy (XPS), revealing the chemical interaction between CPMIMCl with perovskite composition (Figure 2K,L).…”

Lessons learned: how to report XPS data incorrectly about lead-halide perovskites

“…The former attributed the down-shifting of Pb 4f binding energy to increased electron cloud density of the Pb atom due to a strong interaction with PVA/PEG, 31 while the latter believed that the observed up-shifting of the Pb core level was due to decreased electron density by the same polymer via a weaker coordination between the functional groups with Pb than with I À . 32 Likewise, contradictory conclusions have been reported in works about ammonium-salt-modified perovskites: Kang et al TBAPbI 3 (Fig. 3d).…”

Intermediate Phase Engineering with 2,2‐Azodi(2‐Methylbutyronitrile) for Efficient and Stable Perovskite Solar Cells

“…2,2‐Azodi(2‐methylbutyronitrile) (AMBN) has two symmetrical cyano groups (C≡N) that contain lone‐pair electrons from N, leading to coordination with electron‐accepting components. [ 46 ] To show the interaction between AMBN and PbI 2 as well as FAI, coordination exchange experiments were performed. First, AMBN was added to the PbI 2 solution and a change in color was observed after stirring for 3 h. The color change became more evident after three days ( Figure a), whereas the pristine PbI 2 solution showed little change (Figure S1, Supporting Information).…”