The Impact of Backbone Fluorination and Side-Chain Position in Thiophene-Benzothiadiazole-Based Hole-Transport Materials on the Performance and Stability of Perovskite Solar Cells

Abstract

Perovskite solar cells (PSCs) currently reach high efficiencies, while their insufficient stability remains an obstacle to their technological commercialization. The introduction of hole-transport materials (HTMs) into the device structure is a key approach for enhancing the efficiency and stability of devices. However, currently, the influence of the HTM structure or properties on the characteristics and operational stability of PSCs remains insufficiently studied. Herein, we present four novel push-pull small molecules, H1-4, with alternating thiophene and benzothiadiazole or fluorine-loaded benzothiadiazole units, which contain branched and linear alkyl chains in the different positions of terminal thiophenes to evaluate the impact of HTM structure on PSC performance. It is demonstrated that minor changes in the structure of HTMs significantly influence their behavior in thin films. In particular, H3 organizes into highly ordered lamellar structures in thin films, which proves to be crucial in boosting the efficiency and stability of PSCs. The presented results shed light on the crucial role of the HTM structure and the morphology of films in the performance of PSCs.

Alkylsilyl-substituted benzodithiophene-based small molecules as promising hole-transport materials for perovskite solar cells

“…To gather reliable statistics, a total of sixteen devices with the previously described n-i-p configuration were fabricated with each material. 44 The evolution of device efficiency during the experiment is summarized in Fig. S12 (ESI†).…”

Hole-transporting interlayers based on pyrazine-containing conjugated polymers for perovskite solar cells

“…To gather reliable statistics, a total of sixteen devices with the previously described n-i-p configuration were fabricated with each material. 10 Evolution of device efficiency during the experiment is summarized in Fig. 6.…”

“…[4][5][6] One efficient strategy to improve the stability and power conversion efficiency of PSCs is introduction of organic or inorganic charge-transport materials between the perovskite absorber and electrode. [7][8][9][10][11][12][13][14][15] Organic semiconductor materials such as conjugated small molecules or polymers attract considerable attention for application in PSCs due to their unique electronic properties, good conductivity and mechanical flexibility. [16][17][18] These materials can hinder additionally the penetration of moisture to the photoactive layer due to their hydrophobic nature.…”

Remarkable Enhancement of Hole Mobility of Novel DA‐D’‐AD Small Molecules by Thermal Annealing: Effect of the D’‐Bridge Block.

“…In our previous works, we reported the synthesis of a family of thiophene(T)‐benzothiadiazole(B) small molecules with the general formula of TB‐T‐BT, which were shown to be promising components of active layer for organic solar cells, p‐type semiconductor materials for field‐effect transistors, [16] and hole‐transport materials for perovskite solar cells [17] . Although the performance of devices was limited by moderate charge‐transport characteristics of investigated materials.…”