Ba-induced phase segregation and band gap reduction in mixed-halide inorganic perovskite solar cells

Abstract

All-inorganic metal halide perovskites are showing promising development towards efficient long-term stable materials and solar cells. Element doping, especially on the lead site, has been proved to be a useful strategy to obtain the desired film quality and material phase for high efficient and stable inorganic perovskite solar cells. Here we demonstrate a function by adding barium in CsPbI2Br. We find that barium is not incorporated into the perovskite lattice but induces phase segregation, resulting in a change in the iodide/bromide ratio compared with the precursor stoichiometry and consequently a reduction in the band gap energy of the perovskite phase. The device with 20 mol% barium shows a high power conversion efficiency of 14.0% and a great suppression of non-radiative recombination within the inorganic perovskite, yielding a high open-circuit voltage of 1.33 V and an external quantum efficiency of electroluminescence of 10−4.

Tailoring Component Interaction for Air‐Processed Efficient and Stable All‐Inorganic Perovskite Photovoltaic

“…The improved morphology of the MAAc films can be attributed to retard the crystallization process by the interaction between MAAc and PbI 2 and the hydrogen bonds, leading to the increased grain size. This is further confirmed by the significantly enhanced X‐ray diffraction (XRD) peaks intensity at 15.2° and 30.1° arising from (100) and (200) planes of cubic CsPbI 2 Br perovskite structure (Figure c), respectively, with a strong (200) orientation growth. Moreover, the absence of other peaks indicate that the MAAc solvent does not affect the lattice structure of CsPbI 2 Br.…”

Highly efficient all-inorganic perovskite solar cells with suppressed non-radiative recombination by a Lewis base

“…In addition, the CsPbI x Br 3−x film showed larger grain size and a denser morphology after the 6TIC-4F treatment ( Supplementary Fig. 3), which could result in fewer defects on grain boundaries 44,45 and less current leakage in devices 46,47 . In order to distinguish the effect of morphology on the improved performance, the control devices with 6TIC-4F posttreatment (Bilayer 6TIC-4F) were fabricated, and compared with the control devices and devices based on 6TIC-4F-containing antisolvent-treated films.…”

Inorganic Halide Perovskite Solar Cells: Progress and Challenges

“…In fact, the Ba 2+ segregated into Br‐based nonperovskite phases, leading to an increased I/Br ratio in the perovskite layer (Figure 12j,k). [ 109 ] These results contributed to the rapid progress of the research about all‐inorganic PSCs.…”