Spacer Engineering for 2D Ruddlesden–Popper Perovskites with an Ultralong Carrier Lifetime of Over 18 μs Enable Efficient Solar Cells

Abstract

2D Ruddlesden–Popper (RP) perovskites have become emerging photovoltaic materials due to their outstanding optoelectronic properties and intrinsic structure stability. Here, two structurally similar organic spacers with conjugated and unconjugated unites, namely FuMA and THFMA, were developed to study their effects on the photophysical properties of 2D RP perovskites. A very important finding is that the 2D perovskite film (n = 4) based on FuMA with a conjugated furan unit exhibits an ultralong average carrier lifetime of 18.03 μs, which could be attributed to the enlarged dielectric constant, reduced exciton binding energy, and decreased electron–phonon coupling coefficients of the FuMA-based 2D RP perovskites. The optimized device based on the FuMA spacer achieves a high PCE of 18.00% with negligible hysteresis, much higher than that of the THFMA-based device (PCE = 13.79%). This work opens a new avenue for developing 2D RP perovskite films with ultralong carrier lifetimes for photovoltaic and other optoelectronic applications.

Humidity‐Insensitive, Large‐Area‐Applicable, Hot‐Air‐Assisted Ambient Fabrication of 2D Perovskite Solar Cells

“…The LP-150 film possesses the highest τ ave , which indicates it has fewer defects and rationalizes the higher device V OC . [43][44][45] We further quantitatively evaluate defect densities in the LP films using the space charge limited current technique (Figure 4h). Based on the hole-only devices, the defect density of LP-150 is estimated to be 2.02 × 10 15 cm −3 which is significantly lower than that of LP-RT (5.72 × 10 15 cm −3 ).…”

Fast Solidification and Slow Growth Strategy for High‐Performance Quasi‐2D Perovskite Solar Cells

“…Besides, fabricating high-performance quasi-2D PVSCs is still challenging due to their harsh requirement on film morphology, where a highly crystalline and smooth film with vertical orientation is needed. [15,18,[21][22][23] The mostly commonly used strategies to reach the desired morphology include hot-casting, solvent engineering, and additives. [18,[22][23][24][25][26][27] Typically, the quasi-2D perovskite precursor solutions consist of high-boiling point solvents like dimethyl Smooth perovskite film with high crystallinity and vertical orientation is highly favored for high-performance quasi-2D perovskite solar cells (PVSCs), yet limited by the critical balance between nucleation and crystal growth.…”

“…Besides, fabricating high‐performance quasi‐2D PVSCs is still challenging due to their harsh requirement on film morphology, where a highly crystalline and smooth film with vertical orientation is needed. [ 15,18,21–23 ]…”

Highly Improved Efficiency and Stability of 2D Perovskite Solar Cells via Bifunctional Inorganic Salt KPF6 Modified NiOx Hole Transport Layer

“…[11] So far, to continue to improve the PCE of 2D PSCs, researchers have proposed many strategies, such as additive engineering, [12][13][14] interfacial engineering, [15][16][17] and component regulation. [18][19][20][21] Liang and coworkers showed that the addition of 4,5-dicyanoimidazole (DCI) can promote uniform nucleation during perovskite crystallization and got a champion PCE of 17.0% for PEA 2 MA 3 Pb 4 I 13 2D PSCs. [14] Zhang and coworkers reported that an amphoteric imidazole iodide (ImI) was used to passivate 2D perovskites on the surface, thereby improving the mobility of electrons and holes and achieving high efficiency and stability.…”

“…[ 16 ] Besides, Liu and coworkers developed a novel organic spacer salt furan‐2‐yl methanaminium chloride (FuMACl) for 2D PSCs and found that the perovskite film had an extremely long carrier lifetime and achieved a PCE of 18.00%. [ 21 ] However, there is little research on the effect of interface modification of the hole transport layer (HTL) on the performance of 2D PSCs devices.…”