Conjugated Polymer–Assisted Grain Boundary Passivation for Efficient Inverted Planar Perovskite Solar Cells

Abstract

Grain boundaries in lead halide perovskite films lead to increased recombination losses and decreased device stability under illumination due to defect‐mediated ion migration. The effect of a conjugated polymer additive, poly(bithiophene imide) (PBTI), is investigated in the antisolvent treatment step in the perovskite film deposition by comprehensive characterization of perovskite film properties and the performance of inverted planar perovskite solar cells (PSCs). PBTI is found to be incorporated within grain boundaries, which results in an improvement in perovskite film crystallinity and reduced defects. The successful defect passivation by PBTI yields reduces recombination losses and consequently increases power conversion efficiency (PCE). In addition, it gives rise to improved photoluminescence stability and improved PSC stability under illumination which can be attributed to reduced ion migration. The optimal devices exhibit a PCE of 20.67% compared to 18.89% of control devices without PBTI, while they retain over 70% of the initial efficiency after 600 h under 1 sun illumination compared to 56% for the control devices.

Extending the Photovoltaic Response of Perovskite Solar Cells into the Near‐Infrared with a Narrow‐Bandgap Organic Semiconductor

“…More importantly, we observe the presence of F, corresponding to the presence of IEICO‐4F, throughout the depth of the perovskite film, confirming the presence of IEICO‐4F throughout the perovskite layer. This result is consistent with STEM–EDX results reported in the literature in which various Lewis bases were introduced into the perovskite films through the same “loaded dripping strategy” to passivate surface traps . The resulting structure thus resembles the bulk‐heterojunction‐type active layers that are commonly employed in OPVs, and should enable efficient exciton dissociation and charge carrier transfer between IEICO‐4F and CsFAMA.…”

“…It follows that IEICO‐4F should ideally be located at the perovskite grain boundaries to facilitate intergrain charge transfer while preserving intragrain crystallinity. Since perovskite films are commonly grown from a dimethyl sulfoxide (DMSO)‐containing solvent mixture and require an antisolvent treatment to control crystallization, a convenient way to introduce IEICO‐4F into the perovskite layer is to add it to the antisolvent (chlorobenzene, in our case), and deposit the solution during the antisolvent treatment step; a process that is referred to as “loaded dripping strategy” in the literature . With this approach, the additive tends to reside at the perovskite grain boundaries .…”

“…Since perovskite films are commonly grown from a dimethyl sulfoxide (DMSO)‐containing solvent mixture and require an antisolvent treatment to control crystallization, a convenient way to introduce IEICO‐4F into the perovskite layer is to add it to the antisolvent (chlorobenzene, in our case), and deposit the solution during the antisolvent treatment step; a process that is referred to as “loaded dripping strategy” in the literature . With this approach, the additive tends to reside at the perovskite grain boundaries . As an illustration, we delivered IEICO‐4F, predissolved in chlorobenzene (CB), during the spin‐coating of Cs 0.05 (MA 0.17 FA 0.83 ) 0.95 Pb(I 0.83 Br 0.17 ) 3 (CsFAMA) precursors from a solvent mixture of dimethyl formamide (DMF) and DMSO.…”

Triple-cation low-bandgap perovskite thin-films for high-efficiency four-terminal all-perovskite tandem solar cells

“…56 Grain boundaries might result in increased recombination losses and decreased device stability under illumination due to defect-induced ion migration. [57][58][59] Furthermore, SEM images exhibit the formation of bright nanosized aggregates (<100 nm) on the surface of LBG perovskite thin-lms. These aggregates are mitigated by adding Cs and completely disappear by increasing the Cs concentration to 10% (Fig.…”

Progress in the synthesis of imide-based N-type polymer semiconductor materials

“…Besides, the Stille coupling reaction reduced the Br atom content at the end of the corresponding polymer, thus reduced the negative inuence of Br atom on the properties of Polymer semiconductors, too. In 2019, Chen W. et al 62 applied PBTI as a grain boundary passivation in perovskite solar cells. PBTI improved the crystalline properties of the lms and effectively reduced the defects and the carrier recombination, thereby improving PCE and greatly raising the light stability of the device.…”