Non‐Conjugated Polymer as an Efficient Dopant‐Free Hole‐Transporting Material for Perovskite Solar Cells

Abstract

A new non-conjugated polymer (PVCz-OMeDAD) with good solution processability was developed to serve as an efficient dopant-free hole-transporting material (HTM) for perovskite solar cells (PSCs). PVCz-OMeDAD was simply prepared by the free-radical polymerization of vinyl monomers, which were synthesized from low-cost raw materials through three high-yield synthesis steps. The combination of the flexible non-conjugated polyvinyl main chain and hole-transporting methoxydiphenylamine-substituted carbazole side chains endowed PVCz-OMeDAD with excellent film-forming ability, a suitable energy level, and high hole mobility. As a result, by using an ultra-thin (≈30 nm) PVCz-OMeDAD film as cost-effective dopant-free polymer HTM, the conventional n-i-p-type PSCs demonstrated a power conversion efficiency (PCE) up to 16.09 %, suggesting the great potential of the polymer film for future low-cost, large-scale, flexible PSCs applications.

Dopant‐Free Hole Transporting Materials for Perovskite Solar Cells

“…For CH 3 NH 3 PbI x Cl 3–x PSCs, highest PCEs of 15.4 and 16.6% have been achieved for HSL1 and HSL2 based devices, respectively. In a very recent study, Xu et al have been developed a novel non‐conjugated polymer to employ as an efficient dopant‐free HTM for PSCs . PVCz‐OMeDAD ( 32 ) has been obtained by integrating non‐conjugated polyvinyl main chain with carbazole‐based hole transporting side chain.…”

Side‐Chain Engineering on Dopant‐Free Hole‐Transporting Polymers toward Highly Efficient Perovskite Solar Cells (20.19%)

“…As a classic and standard HTM, 2,2′,7,7′‐tetrakis(N,N‐di‐ p ‐methoxyphenyl‐amine)‐9,9′‐spirobifluorene (spiro‐OMeTAD) yielded the highest PCE so far of 24.2%, however, it requires doping treatment by oxidants to enhance its hole conductivity, which always inevitably leads to the consequences of long fabrication duration and poor long‐term stability for the PSC devices . As a result, numerous dopant‐free organic substitutes including small molecules and polymers have been developed, and reports of PCE values of over 19% have been frequently issued. Although PCEs of 20.5 and 23.3% were also released, this high efficiency was obtained through optimizing the ETM layer or the perovskite layer, while the HTM itself was earlier designed/employed and reported with a PCE of only 18.3 or 0.52% at its first appearance.…”

Hole Transport Materials in Conventional Structural (n–i–p) Perovskite Solar Cells: From Past to the Future

“…In 2016, a device employing PTAA with methylphenylethenyl groups ( V873 ) exhibited 12.29% of efficiency without dopants ( Figure 5 ). As another concept, some groups reported side‐chain polymers, including non‐conjugated polyvinyl main chains with hole transport side‐chains . They generally have properties of good electron‐blocking capacity and excellent film formability.…”