An Embedding 2D/3D Heterostructure Enables High‐Performance FA‐Alloyed Flexible Perovskite Solar Cells with Efficiency over 20%

Abstract

Flexible perovskite solar cells (f-PSCs) have attracted increasing attention because of their enormous potential for use in consumer electronic devices.The key to achieve high device performance is to deposit pinhole-free, uniform and defect-less perovskite films on the rough surface of polymeric substrates. Here, a solvent engineering to tailor the crystal morphology of FA-alloyed perovskite films prepared by one-step blade coating is first deployed. It is found that the use of binary solvents DMF:NMP, rather than the conventional DMF:DMSO, enables to deposit dense and uniform FA-alloyed perovskite films on both the rigid and flexible substrates. As a decisive step, an embedding 2D/3D perovskite heterostructure is in situ formed by incorporating a small amount of 4-guanidinobutanoic acid (GBA). Accordingly, photovoltage increases up to 100 mV are realized due to the markedly suppressed nonradiative recombination, leading to high efficiencies of 21.45% and 20.16% on the rigid and flexible substrates, respectively. In parallel, improved mechanical robustness of the flexible devices is achieved due to the presence of the embedded 2D phases. The results underpin the importance of morphology control and defect passivation in delivering high-performance flexible FA-alloyed flexible perovskite devices.

Roles of Long‐Chain Alkylamine Ligands in Triple‐Halide Perovskites for Efficient NiOx‐Based Inverted Perovskite Solar Cells

“…The J−V hysteresis can be remarkably suppressed in BSLP‐based solar cells as compared with the control and SLP‐based devices, which indicates the fact that OmA‐based 2D perovskites are embedded at GBs of 3D crystal grains. [ 25 ] Such results further confirm that OmA‐based 2D perovskites embedded at the GBs of 3D crystal grains can suppress charge recombination and ion migration. [ 41,42 ] Note that the BSLP‐based solar cells also show higher J sc values attributed to the stronger light absorption (Figure 2a) and higher thickness of the perovskite layer (Figure 1g,h).…”

“…Especially, secondary growth can rearrange the GBs and minimize the surface energy and defects of perovskite films, which enable highly efficient and stable PSCs. [ 24,25 ] In addition, 2D perovskites have superior stability against humidity, light exposure, and heat stress because of their hydrophobic properties arising from the aliphatic‐ or aromatic‐based organic spacers. Therefore, to build a 2D@3D perovskite heterostructure is also a significant way to passivate perovskite interface defects for improving efficiency and stability.…”

PTAA as Efficient Hole Transport Materials in Perovskite Solar Cells: A Review

“…Recently, the highest reported PCE for flexible PSCs reached >20% using PTAA‐based p–i–n structures. [ 200 ] Furthermore, Wu et al recently reported a perovskite/organic hybrid solar cell, which achieved a PCE of 21.73% on PTAA/ITO/PEN substrates. [ 164 ] It has been shown that PTAA is potentially one of the most suitable HTLs for flexible PSCs, especially for p–i–n structures.…”

Quasi-2D halide perovskite crystals and their optoelectronic applications

“…One merit of 2D halide perovskites is their wide property tunability resulting from facile and flexible composition engineering. 31–36 They can be substituted completely or partially by other similar ions. Additionally, adjusting the n value has a significant impact on their optoelectronic properties.…”