Self‐Doped Conducting Polymer as a Hole‐Extraction Layer in Organic–Inorganic Hybrid Perovskite Solar Cells

Abstract

mesoporous charge transfer layer, their application into the fl exible electronics would be limited due to their brittleness and the high-temperature (i.e., T > 450 °C) sintering process which damages plastic substrates. Otherwise, solutionprocessed planar heterojunction (SP-PHJ) PrSCs can be fabricated using low-temperature processable interlayers without mesoporous metal oxides; this approach enables the fabrication of fl exible PrSCs on plastic substrates. [7][8][9] Therefore, the development of a solution-processed and effi ciently charge-transporting interlayer material has been required recently to increase PCE of SP-PHJ PrSCs for the practical application of highly effi cient and fl exible PrSCs. In addition to conducting polymers (e.g., poly(3,4-ethylen edioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), [ 7,9,15,16 ] self-organized hole extraction layer (SOHEL) [ 9 ] ), several different hole transport materials (HTMs), including inorganic materials (graphene oxide, [ 17 ] reduced graphene oxide, [ 18 ] NiO x [ 15 ] ) and conjugated polymers (e.g., PolyTPD, [ 19 ] P3HT, [ 20 ] poly(2,5-(2-octyldodecyl)-3,6-diketopyrrolopyrrole-alt-5,5-(2′,5′di(thien-2-yl)thieno[3,2-b]thiophene) (DPP-DTT), [ 21 ] PCP-DTBT, [ 21 ] and PCDTBT [ 21 ] ) have been used to increase the PCE in SP-PHJ PrSCs.Among these materials, polymeric HTMs have been intensively developed for highly effi cient SP-PHJ PrSCs because they can be fabricated by solution processing and exhibit better hole mobility compared to vacuum-processed small-molecule HTMs. [ 3 ] In the fi rst few papers reporting SP-PHJ PrSCs, they were based on the PEDOT:PSS HTM [ 16 ] because PEDOT:PSS is one of the most commonly used HTMs for organic photovoltaics [22][23][24][25][26][27] and organic light-emitting diodes (OLEDs). [ 28,29 ] However, work function (WF) of PEDOT:PSS (≈4.9-5.2 eV) is highly dependent on the ratio of the polymeric acid, PSS relative to PEDOT [ 25,28 ] and therefore may not be suffi ciently high to perfectly match the valence band maxima (VBM) of perovskite materials (e.g., -5.43 eV for methylammonium lead iodide (MAPbI 3 )) for ohmic contact and consequential effi cient charge extraction. [ 9,15,[19][20][21][22][23][24][25][26][27][28][29] Moreover, PEDOT:PSS is dispersed with a large particle size (≈60 nm) in solution; [ 30 ] it precipitates slowly from the solution during storage and is diffi cult to redisperse from the aggregated Organic-inorganic hybrid perovskite solar cells are fabricated using a watersoluble, self-doped conducting polyaniline graft copolymer based on poly(4styrenesulfonate)-g -polyaniline (PSS -g-PANI) as an effi cient hole-extraction layer (HEL) because of its advantages, including low-temperature solution processability, high transmittance, and a low energy barrier with perovskite photoactive layers. Compared with conventional poly(3,4-ethylenedioxythiop hene):poly(styrene sulfonate) (PEDOT:PSS) dispersed in water solution, PSSg-PANI molecules are dissolved in water because of the polymeric dopant covalently bonde...

Solution‐Processable Conjugated Polymers as Anode Interfacial Layer Materials for Organic Solar Cells

“…[69] Furthermore, chemical modification of PANI along with molecular doping has been found to be an effective strategy www.advancedsciencenews.com for further improving the hole transport property of PANI, through introducing the intramolecular interaction of covalent bonding or the supramolecular interaction. [74] For the hybrid solar cell with a device structure ITO/AIL/ MAPbI 3 /PCBM/Al, the PCE of the device using PSSA-g-PANI as AIL could reach 9.7%, which was higher than the 7.8% for the device with PEDOT:PSS. [70] For example, p-toluene sulfonic acid (TSA − ) as the dopant was incorporated into SPANs to form the TSA − doped SPANs (SPAN-TSA − ).…”

Metal Oxides as Efficient Charge Transporters in Perovskite Solar Cells

“…[46][47][48][49] In this architecture, the perovskite layer is directly deposited on the compact TiO 2 layer (Figure 2b). [46][47][48][49] In this architecture, the perovskite layer is directly deposited on the compact TiO 2 layer (Figure 2b).…”

Hybrid Perovskites: Effective Crystal Growth for Optoelectronic Applications

“…PEDOT:PSS/Perfluorinated ionomer) is mostly adopted in p-i-n structure. [60,88,89] Similar to the ETM, the modification of HTMs by polymer mixture, lithium salt doping and chemical modification enhances energy level matching and conductivity of materials. [90][91][92][93] Nonetheless, recent researches are moving toward dopant-free HTMs, such as NiO, as deliquescent nature of dopant may readily aggravate device performance.…”