Creating a Dual‐Functional 2D Perovskite Layer at the Interface to Enhance the Performance of Flexible Perovskite Solar Cells

Abstract

Flexible perovskite solar cells (f‐PSCs) have been attracting tremendous attention due to their potentially commercial prospects in flexible energy system and mobile energy system. Reducing the energy barriers and charge extraction losses at the interfaces between perovskite and charge transport layers is essential to improve both efficiency and stability of f‐PSCs. Herein, 4‐trifluoromethylphenylethylamine iodide (CF3PEAI) is introduced to form a 2D perovskite at the interface between perovskite and hole transport layer (HTL). It is found that the 2D perovskite plays a dual‐functional role in aligning energy band between perovskite and HTL and passivating the traps in the 3D perovskite, thus reducing energy loss and charge carrier recombination at the interface, facilitating the hole transfer from perovskite to the Spiro‐OMeTAD. Consequently, the photovoltaic performance of f‐PSCs is significantly improved, leading to a power conversion efficiency (PCE) of 21.1% and a certified PCE of 20.5%. Furthermore, the long‐term stability of f‐PSCs is greatly improved through the protection of 2D perovskite layer to the underlying 3D perovskite. This work provides an excellent strategy to produce efficient and stable f‐PSCs, which will accelerate their potential applications.

Ionogel-perovskite matrix enabling highly efficient and stable flexible solar cells towards fully-R2R fabrication

“…In terms of efficiency, mechanical stability and operational stability, the IG-PVK devices are at the forefront of the reported flexible PSCs, even compared to spin-coated devices (Table S1, ESI †). [1][2][3][4][5]9,27,28,[37][38][39][40][41][51][52][53][54][55][56] The extensively tunable IG matrix, as a platform containing rich interactions, through its modification and collaboration with perovskite endows flexible devices with robust mechanical properties, inhibition of ion migration, passivation of multiple interfaces, prevention of lead leakage, 57 etc., infinite possibilities. We believe that ionogel will play more important and unique roles on the road to the commercialization of flexible perovskite solar cells.…”

Multifunctional Compound‐Regulated SnO2 for High‐Efficiency and Stable Perovskite Solar Cells under Ambient Air

“…2 -(E c -E f ). [48] The E v of SnO 2 and KPAB-SnO 2 were calculated to be À 8.33 and À 8.29 eV, respectively. In addition, to calculate the bandgaps (E g ) of SnO 2 and KPAB-SnO 2 ETL, the UV-vis spectra of ETLs were recorded and shown in Figure 4c.…”

Recent advances in the interfacial engineering of organic–inorganic hybrid perovskite solar cells: a materials perspective

“…In contrast to the above research directions, Long et al worked out the effect of a 2D perovskite on flexible PSCs. 118 They introduced a 2D perovskite formed from 4-trifluoromethylphenylethylamine iodide (CF 3 PEAI) on the surface of a 3D perovskite. The 2D perovskite not only improved the energy-level alignment between the HTL and the perovskite layer but also reduced the trap density in the 3D perovskite, lowering the energy loss and carrier recombination at the interface and promoting hole transfer from the perovskite to the HTL.…”