Star‐Shaped Organic Semiconductor with Extraordinary Thermomechanical Property and Solution Processability for Stable Perovskite Solar Cells

Abstract

Achieving the desired thermomechanical properties for highly solution‐processable organic semiconductors is challenging but crucial for heat tolerance of emerging optoelectronic devices. To this end, the successful synthesis of triphenylene–ethylenedioxythiophene‐dimethoxytriphenylamine (TP–ETPA), a star‐shaped organic semiconductor, is reported through a direct arylation reaction that involves ETPA, an electron donor, being grafted densely onto TP, which possesses six electron‐equivalent functionalization sites. Remarkably, TP–ETPA exhibits significantly improved hole mobility compared to 2,2′,7,7′‐tetrakis(N,N‐di‐p‐methoxyphenyl‐amine)‐9,9′‐spirobifluorene (spiro‐OMeTAD) at a given hole density, owing to its lower energetic disorder, larger average centroid distance, and smaller reorganization energy. TP–ETPA, with a molecular weight of 2888 Da and lacking flexible chains, demonstrates extraordinary solubility in nonpolar solvents, enabling the formation of dense, pinhole‐free films through solution codeposition with an air‐doping promoter. By utilizing the p‐doped TP–ETPA composite as the hole transport layer, perovskite solar cells with an average power conversion efficiency of 23.4% are successfully fabricated. Notably, these devices display significantly enhanced operational stability and thermal stability at 85 °C. Molecular dynamics simulations reveal that the TP–ETPA‐based hole transport layer possesses a high cohesive energy density, resulting in a large elastic modulus and slow diffusion of external species.

Triisocyanate Derived Interlayer and High‐Melting‐Point Doping Promoter Boost Operational Stability of Perovskite Solar Cells

“…By employing TBPHHFSI as an air-doping promoter for the HTL, the cell demonstrated significantly enhanced stability at 65 °C under a nitrogen atmosphere, with a P MPP retention rate of 92 % after 500 hours. This underscores the pivotal role of controlling ion migration in the HTL to augment the operational stability of PSCs, necessitating the judicious selection of high cohesive energy density organic semiconductors [53,54] and suitable air-doping promoters.…”

Hole-transporting alternating copolymers for perovskite solar cells: thia[5]helicene comonomer outperforms planar perylothiophene analog

“…[7][8][9] Nevertheless, its deep HOMO energy level poses challenges in achieving sufficiently high conductivity through air doping, resulting in suboptimal PCE when applied to n-i-p-type PSCs. Additionally, while a diverse array of molecular semiconductors and polymeric semiconductors with varied structures has found utility in PSCs, [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] only a select few materials successfully balance efficiency, stability, and cost.…”

Aza[5]helicene‐Derived Semiconducting Polymers for Improved Performance in Perovskite Solar Cells: Exploring Energetic and Morphological Influences

“…Indeed, molecular semiconductor films with low glass transition temperatures ( T g ) experience conspicuous morphology degradation under heating. Additionally, water, oxygen, and certain ions readily diffuse in these low cohesive energy density, high free volume HTLs [13] . Another frequently employed p‐type organic semiconductor substitute in PSCs is PTAA (Figure 1); [14] however, due to its deeper HOMO energy level, achieving sufficiently high conductivity through air doping proves challenging, resulting in suboptimal PCEs when applied to n‐i‐p PSCs [9,15] .…”