Synergistic Effect between NiO_x and P3HT Enabling Efficient and Stable Hole Transport Pathways for Regular Perovskite Photovoltaics

Abstract

As an inorganic hole transport material (HTM), nickel oxide (NiOx) is widely used in perovskite solar cells (PSCs) due to its low cost and intrinsic stability. However, on account of its poor film formation on perovskite, the low power conversion efficiency (PCE) and stability of regular NiOx‐based PSCs is a main obstacle for commercialization. Here, a solution‐processed inorganic/organic hybrid hole transporting system is developed to resolve this issue, thereby improving the PCE from 16.0% to 21.2%. Poly(3‐hexylthiophene) (P3HT) is studied as the typical case, revealing that the performance improvement mainly lies in the synergistic interaction between NiOx and P3HT: 1) the introduction of P3HT improves assembly regularity and film uniformity of NiOx; 2) electron redistribution between P3HT and NiOx increases the Ni3+/Ni2+ ratio for higher hole mobility; 3) the feed‐back impact of NiOx on P3HT enhances molecular orientation of polymer chains in P3HT for better hole transport through polymer framework. Finally, the encapsulated solar cell modules with P3HT‐promoted NiOx maintains 91% of the initial efficiency after 1000 h aging at a harsh 85 °C/85% relative humidity condition. This finding provides a feasible approach for using NiOx‐based HTMs to realize high‐performance regular PSCs, paving the way for their commercialization.

85 °C/85%‐Stable n‐i‐p Perovskite Photovoltaics with NiOx Hole Transport Layers Promoted By Perovskite Quantum Dots

“…Perovskite solar cells (PSCs) have reached remarkable certified power conversion efficiencies (PCEs) up to 25.7% with n‐i‐p configuration. [ 1 ] In the n‐i‐p devices, p‐type organic semiconductors (e.g., spiro‐OMeTAD, [ 2 ] PTAA, [ 3 ] P3HT [ 4 ] ) have been usually chosen as hole transport layers (HTLs) to achieve high PCEs. However, the intrinsic photothermal instability or external hydrophilic ionic doping of these organic HTLs limits their further application in commercial manufacture.…”

Turning copper into gold: cost-effective positive electrodes for high-performance perovskite solar cells

“…The residue was nally puri ed by silica gel column chromatography (ethyl acetate/ petroleum ether = 1/10 Then the substrate with perovskite precursor was heated at 110°C for 20 minutes. For spiro-OMeTAD as hole transport layer, spiro (71 mg/mL in chlorobenzene with 8.6 µL of 520 mg/mL Li-TFSI/acetonitrile and 14.4 µL of 4-tertbutylpyridine (TBP)) was spin coated at 4000 rpm for 20 s. For NiO x as hole transport layer (HTL), the synthesis and deposition methods followed our group's previous report 32 . The HTL was 85 wt% NiO x + 15 wt% P3HT, and omitted as NiO x here.…”

“…The above ndings can be applied to n-i-p devices with NiO x , an inorganic HTL which is considered to be more stable than most organic HTLs 32 . NiO x has a lower valence band (-5.21 eV, Supplementary g. 31) compared to spiro, so that E F and E OX of the modi ed Cu electrode should be further lowered.…”

Managing the Double-Edged Sword of Ni3+ in Sputter-Deposited NiOx by Interfacial Redox Reactions for Efficient Perovskite Solar Cells

“…Many efforts have been devoted to improving the PCE of PSCs based on magnetron-sputtered NiO x (sp-NiO x ). ,− Despite all the advantages of magnetron sputtering, PCE of the sp-NiO x -based PSCs are still lagging behind those with solution-processed NiO x . , Low PCE likely originates from the prominent Ni 3+ issue in sp-NiO x , as Ni 3+ exhibits a double-edged sword effect in NiO x . On the one hand, a high concentration of Ni 3+ in the bulk provides holes and p-type properties for NiO x , which is necessary to achieve good charge transport in the bulk. , On the other hand, it is reported that excess Ni 3+ at the sp-NiO x surface may induce decomposition of the perovskite layer, leading to the loss of A-site cations and I – from the perovskite structure and leaving residual PbI 2 into the perovskite films. ,,, This produces all kinds of unwanted defects and chemical species at the interface, which causes carrier recombination and impedes charge transport. A higher Ni 3+ concentration can often be obtained with magnetron sputtering compared to with the solution method, , which promises better charge transport in the NiO x film.…”

“…On the one hand, a high concentration of Ni 3+ in the bulk provides holes and p-type properties for NiO x , which is necessary to achieve good charge transport in the bulk. 6,34 On the other hand, it is reported that excess Ni 3+ at the sp-NiO x surface may induce decomposition of the perovskite layer, leading to the loss of A-site cations and I − from the perovskite structure and leaving residual PbI 2 into the perovskite films. 29,33,35,36 This produces all kinds of unwanted defects and chemical species at the interface, which causes carrier recombination and impedes charge transport.…”