Methoxy-Functionalized Triarylamine-Based Hole-Transporting Polymers for Highly Efficient and Stable Perovskite Solar Cells

Abstract

The hole-transporting layer is an essential component in a perovskite solar cell (PSC) and plays a key role in controlling both power conversion efficiency (PCE) and stability. Here, we report a new hole-transporting material (HTM), methoxy groupcontaining poly(triarylamine) (PTAA) (CH 3 O-PTAA), for efficient PSCs with improved thermal stability. As compared to commonly used PTAA (CH 3 -PTAA), CH 3 O-PTAA exhibits enhanced doping ability and stability under thermal stress. With CH 3 O-PTAA, (FAPbI 3 ) 0.85 (MAPbBr 3 ) 0.15 -based PSCs show high PCEs over 20%, comparable to those of CH 3 -PTAA devices. More importantly, better long-term thermal stability with only 3% reduction from the initial PCE (6.1% reduction on average) has been achieved for encapsulated PSCs with CH 3 O-PTAA than that of PSCs with CH 3 -PTAA under dark storage conditions (ISOS-D-3) of 85 °C and 85% relative humidity (RH) over 1000 h. Detailed studies have been conducted to reveal the strong correlation between the doping behavior of HTMs and the performance of PSCs, which provide useful guidelines for the design of new HTMs for efficient and stable PSCs.

Solubility of Hybrid Halide Perovskites in DMF and DMSO

“…To further understand the effect of mixed compositions on the total solubility of the perovskite, we also measured the solubility of one of the best compositions for perovskite solar cells (MAPbBr 3 ) 0.15 (FAPbI 3 ) 0.85 at 30 • C and 90 • C [22,25]. In practice, mixed DMSO-DMF solvent is commonly used; therefore, we also tested the solubility of (MAPbBr 3 ) 0.15 (FAPbI 3 ) 0.85 in the mixture of DMF and DMSO (4:1 v/v).…”

Metal‐Free Phthalocyanine as a Hole Transporting Material and a Surface Passivator for Efficient and Stable Perovskite Solar Cells

“…The PSCs with a n‐i‐p structure with organic hole transport materials (HTM) are vulnerable to heat despite offering a higher PCE than the PSCs with a p‐i‐n structure, and researchers have thus sought to discover thermally stable HTMs. A few polymeric HTMs such as poly(triaryl amine) (PTAA), [ 7 ] molecular HTMs such as metal phthalocyanines, [ 8 ] and an inorganic HTM, cuprous thiocyanate, [ 9 ] have shown long‐term stability at 85 °C with PCE exceeding 20%. We have reported that PSCs with application of copper phthalocyanine (CuPc) showed outstanding thermal stability up to 110 °C and temperature cycles.…”

A Perylene‐Based Conjugated Polymer Endows Perovskite Solar Cells with 85 °C Durability: The Control of Gas Permeation

“…In high-efficiency n-i-p typed PSCs, spiro-OMeTAD and p-TAA (Figure 1) are so far the most commonly used smallmolecule and polymeric hole transport materials (HTMs) for PSCs, respectively. [4][5][6][7]18,19] Actually, even a thin film of neat spiro-OMeTAD or p-TAA with a thickness of only a few tens of nanometers owns a considerable resistance, [18,20,21] which cannot meet the requirement of low internal resistance in high-efficiency PSCs. Several reports have shown that thin films of doped spiro-OMeTAD with improved electrical conductivity [22,23] can be used to prepare high-efficiency PSCs, but the resultant devices encounter severe PCE degradations at 85 °C.…”

“…[24,25] In contrast, although the film-forming property of p-TAA is better, the PCEs of PSCs fabricated with thin films of doped p-TAA are always reduced due to lower conductivity, and the device thermostability at 85 °C is still far from ideal. [18] Apart from p-TAA, regioregular poly(3hexylthiophene) (P3HT, Figure 1) has also been tested as HTL of PSCs. [26,27] With respect to p-TAA, P3HT has a larger driving force for hole extraction and a higher hole mobility, but its charge recombination with perovskite is faster probably owing to the excessive interface interaction, [28] thereby it is hard to be used for high-efficiency PSCs if a delicate interfacial layer is not well inserted.…”