Stable Perovskite Solar Cells Enabled by Simultaneous Surface and Bulk Defects Passivation

Abstract

It is challenging to passivate defects that are buried in the depth of perovskite films; most of the reported passivation methods cannot reach the deep defects. Herein, methanol is adopted as a dual‐functional reagent to not only act as a solvent but also help the dissolved ions penetrate the depth of perovskite films. By treating the as‐prepared perovskite films with CsBr/methanol solution, Br− ions can react with the undercoordinated Pb2+, and Cs+ ions can fill in the cation vacancies. This strategy enables surface and bulk defects passivation to be achieved simultaneously. The nonradiative recombination of the double‐passivated devices is significantly suppressed and the migration of charged defects is remarkably hindered. As a result, an improved power conversion efficiency of 19.5% and an open‐circuit voltage of 1.183 V is achieved. Moreover, the passivated device can retain ≈80% of the initial efficiency after working for 500 h at maximum power point under 1‐sun illumination, whereas the pristine device reaches 80% of the initial efficiency after only 90 h. This work demonstrates that surface and bulk defects passivation is critical to improve the efficiency and long‐term operational stability of the perovskite solar cells.

Moisture-triggered fast crystallization enables efficient and stable perovskite solar cells

“…Depositing high-quality perovskite films with few defects plays a crucial role in achieving efficient and stable perovskite solar cells (PSCs) [1][2][3][4][5][6][7] . Perovskite bulk doping and interface modification have been demonstrated to be effective in suppressing the bulk and interfacial defects [8][9][10][11][12][13] . It is reported that the perovskite formation process is sensitive to the surrounding atmosphere, like the solvent vapor, moisture, and others [14][15][16][17][18] .…”

The Influence of CsBr on Crystal Orientation and Optoelectronic Properties of MAPbI3-Based Solar Cells

“…A change in the tolerance factor can inevitably lead to a mismatch of the crystal lattice constant and explain the observed peak shifts in the XRD characterization . Therefore, the gradual shift of the characteristic peaks of the perovskite phase to higher diffraction angles can be attributed to the substitution of the vacant MA + and I – sites in the host perovskite by Cs + and Br – , which have smaller ionic radii, thereby decreasing the residual stress and decreasing the lattice constant . Thus, it is suggested that CsBr is integrated into the perovskite lattice.…”

Wide Bandgap Interface Layer Induced Stabilized Perovskite/Silicon Tandem Solar Cells with Stability over Ten Thousand Hours

“…Furthermore, the extra Cs + and Br − can bond with negatively‐charged defects (lead vacancy) and positively‐charged defects (halogen vacancy) through ionic bonds at the bottom of perovskite, reducing the non‐radiative recombination channel. [ 42 ] Additionally, the ions diffusion between the interface of CsBr and perovskite allows for Br − partially exchanging I − to form Br‐rich phase at the bottom of perovskite, appropriately expanding the bottom perovskite bandgap, achieving an ideal band bending and a better energy level alignment. [ 23,43–47 ]…”