Poly(N,N′‐bis‐4‐butylphenyl‐N,N′‐biphenyl)benzidine as Interfacial Passivator for Dopant‐Free P3HT Hole Transport Layer‐Based Perovskite Solar Cell in Regular Mesoscopic Architecture

Abstract

The best‐recorded performance of perovskite‐based solar cells (PSCs) in regular mesoscopic architecture is generally associated with the use of the common 2,2′,7,7′‐tetrakis[N,N‐di(4‐methoxyphenyl)amino]‐9,9′‐spirobifluorene (Spiro‐OMeTAD). However, the need for lithium‐based hygroscopic dopants hinders the chemical and environmental stability of the devices. This work presents a passivated stable PSC device based on a dopant‐free poly(3‐hexylthiophene) (P3HT) hole transport layer. By introducing a poly(N,N′‐bis‐4‐butylphenyl‐N,N′‐biphenyl)benzidine (polyTPD) interlayer at the perovskite/P3HT interface, the parameters of the low‐performance pristine P3HT‐based cells are improved. This introduction leads to optimizing the P3HT film morphology, interfacial defects, and charge extraction, along with a significant suppression of interfacial recombination and enhancement of the cell power conversion efficiency (PCE) from 7% to 10.65%. Further, an improvement is observed in open‐circuit voltage and the fill factor, increasing from 0.912 to 0.95 V and from 59.2% to 61.1%, respectively. Moreover, the noncapsulated passivated PSC devices exhibit higher operational stability. Examinations show that devices in a dark controlled environment (10–15% humidity) can retain 82% of their initial PCE for 450 h, and 73% of their initial PCE when thermally stressed at 60 °C temperature under ambient conditions (25–35% humidity) for 264 h.

Recent Advances in Poly(3‐hexylthiophene) and Its Applications in Perovskite Solar Cells

“…[31] Additionally, P3HT has strong resistance to mechanical stress and was applied in flexible PSC applications. [66,73] The highest occupied molecular orbital energy level (E HOMO ) of P3HT is near À5.2 eV, [8] which is greater than that of perovskite materials (methylammonium lead iodide and mixed perovskite have an E HOMO of À5.4 and À5.6 eV, respectively). [74,75] It is important to note that P3HT has a relatively higher hole mobility (up to 0.1 cm 2 V À1 s À1 depending on its π-stacking and chain organization), [31,39,40,52,62,63] compared to pristine Spiro-OMeTAD (≈10 À4 cm 2 V À1 s À1 according to space charge limited current [SCLC] calculations).…”

“…[8,115,[122][123][124][125] Organic compounds such as PolyTPD, P3CT-BN, and BTCIC-4Cl were inserted as buffer layers at the perovskite/P3HT interface. [8,115,123] These inserted layers were able to coordinate with the uncoordinated Pb 2þ atoms at the perovskite surface, which increased hole extraction and decreased interfacial trap states and charge-carrier recombination, with the highest recorded performance attributed to P3CT-BN-based devices, achieving a 19.23% PCE while retaining 80% of its initial PCE under 40% relative humidity for 1800 h. [115] Another combination was reported based on P3HT NPs and trioctylphosphine oxide (TOPO) interlayer for carbon electrodebased PSCs. The introduced combination preserved a significantly improved performance of 18.4% PCE with thermal stability under thermal stress for 1000 h, while with Au electrode recorded a high 19.8% PCE.…”

“…[1] After that, the perovskite started gaining a significant focus from many research groups due to its favorable photovoltaic characteristics, including low exciton binding energy, high absorption, long charge-carrier diffusion length, direct and tunable bandgap energy, and ambipolar charge transport properties. [2][3][4][5][6][7][8] The first perovskite solar cell (PSC) was a replicate of the dye-sensitized solar cell with the perovskite sensitizer replacing the conventional dye. [1] Unfortunately, that device structure suffered an unstable low performance (3.8% power conversion efficiency [PCE]) due to the liquid electrolyte role in perovskite degradation.…”

A comparative study of different poly(3-hexylthiophene)–carbon based hole transport layers on the stability of perovskite solar cells prepared under ambient conditions

“…However, its LUMO level is higher (∼ 3.0 eV) than that of spiro-OMeTAD (∼ 1.7 eV), leading to a larger charge carrier recombination at the perovskite/P3HT interface and consequently making it less effective as an electron blocker. To reduce such recombination, several interfacial modification strategies have been reported (Jung et al, 2019;Zhang et al, 2020;Jeong et al, 2021;Peng et al, 2022;Guo et al, 2021;Gu et al, 2022;Kassem et al, 2022;Ghoreishi et al, 2022;Li et al, 2022). The most successful one has been the introduction of a thin layer of wide-bandgap halide perovskite on the perovskite surface (Jung et al, 2019), together with the addition of gallium (III) acetylacetonate in P3HT, leading to very efficient (∼ 24%) and stable PSCs (Jeong et al, 2021).…”