Carbazole-Based Hole Transport Polymer for Methylammonium-Free Tin–Lead Perovskite Solar Cells with Enhanced Efficiency and Stability

Abstract

As the most commonly used hole transport material (HTM) in tin–lead (Sn–Pb) perovskite solar cells (PSCs), poly­(3,4-ethylenedioxythiophene) polystyrenesulfonate (PEDOT:PSS) limits the power conversion efficiency (PCE) and stability of the PSCs due to its acidic characteristics. Herein, an easily synthesized polymer HTM poly­[(phenyl)­imino­[9-(2-ethylhexyl)­carbazole]-2,7-diyl] (CzAn) with a shallow highest occupied molecular orbital (HOMO) level of −4.95 eV is used in a p-i-n structure, methylammonium-free, Sn–Pb PSC to replace PEDOT:PSS. Upon optimization using doping and surface engineering, high quality Sn–Pb PSCs could be successfully fabricated, boosting the PCE to 22.6% (stabilized PCE of 21.3%) compared with 21.2% for PEDOT:PSS. The perovskite films prepared on the modified CzAn HTM possess improved crystallinity, reduced trap-state density, and larger carrier mobility resulting in PSCs with greatly improved stability.

Prospects for Tin-Containing Halide Perovskite Photovoltaics

“…All of these routes lead to imperfect materials and accordingly reduce the efficiency of Sn-containing PSCs. Alternative strategies, such as modified PEDOT/PEDOT-free HTLs/SAM-based HTLs (HTL denotes hole-transport layer), ,− surface/interface postmodification, ,, DMSO-free or solvent-free , processing systems, and material encapsulation techniques, that efficiently work for Sn-containing perovskites are thus a pressing area for reducing the effect of Sn­(II) oxidation in perovskites.…”

“…To this end, removing volatile organic content from the perovskite (such as MA + ) will likely be necessary. For mixed Sn–Pb PSCs, reducing the efficiency gap between MA-containing and MA-free cells will need significant further investigation, , especially on understanding/altering the crystallization dynamics.…”

“…To this end, removing volatile organic content from the perovskite (such as MA + ) 113 will likely be necessary. For mixed Sn−Pb PSCs, reducing the efficiency gap between MA-containing and MA-free cells will need significant further investigation, 66,67 especially on understanding/altering the crystallization dynamics. Most commonly used solvents are toxic with damaging environmental impacts and therefore are heavily regulated in industry, so alternative less toxic solvent systems should be a priority for Sn perovskites, as with Pb.…”

Graphene‐Like Conjugated Molecule as Hole‐Selective Contact for Operationally Stable Inverted Perovskite Solar Cells and Modules

“…Many aromatic systems with the electron‐donating ability, such as triarylamines, carbazoles, and polythiophene, have been employed as the π‐conjugated building blocks of hole‐selective molecules. [ 19–24 ] Poly(bis(4‐phenyl)(2,4,6‐trimethylphenyl)amine) (PTAA) is a commonly‐used triarylamine‐based hole‐selective contact to produce high‐performance inverted PSCs with an operational T 80 lifetime (the time over which the efficiency reduces to 80% of its initial value) of 1000–1500 h. [ 25,26 ] However, additional surface modifications are needed to improve the interface quality between PTAA and the perovskite layer when further enlarging the device area. [ 27,28 ] To address this issue, Chen et al.…”

N,N-Bis(9-methyl-3-carbazolyl)-4-anisidine as an Electroactive Material for Use in Perovskite Solar Cells

“…1 H NMR spectrum of DMCAA in acetone-d 6 (FigureS3);13 C NMR spectrum of DMCAA in acetone-d 6 (FigureS4); 1 H NMR spectrum of DMCAA in benzene-d 6 (FigureS5);13 C NMR spectrum of DMCAA in benzene-d 6 (Figure S6); mass spectrum (MS) of DMCAA (Figure S7); FT-IR spectrum of DMCAA (Figure S8); an establishment of transient times (ttr) for holes (positive current) and electrons (negative current) in the double logarithmic scale (both for time and current) from the kink of transient currents (Figures S9 and S10); shape of frontier orbitals and UV spectra of DMCAA calculated at B3LYP/6-31G(d)/CPCM (acetonitrile) (Figures S11 and S12); J−V characteristics of p−i−n-type devices DMCAA without additives (Figure S13) (PDF) ■ AUTHOR INFORMATION Corresponding Authors…”