Green-solvent-soluble, highly efficient dopant-free hole-transporting material for perovskite solar cells

Abstract

Halogenated solvents (e.g., chlorobenzene and chloroform) are typically used for hole-transporting materials (HTMs) in perovskite solar cells (PSCs); however, their use should be avoided as they are known to be hazardous to the environment. Herein, we synthesized a nonhalogenated-solvent-soluble, dopant-free HTM, SF62. When depositing HTMs for PSCs, SF62 could be dissolved with a nonhalogenated and green solvent, ethyl acetate. It is one of the most common organic solvents and is known to have a low environmental impact. Non-doped-SF62-based PSCs exhibited higher power-conversion efficiency (18.6%) than doped 2,2',7,7'-tetrakis(N,N-di-p-methoxyphenylamino)-9,9'-spirobifluorene (Spiro-OMeTAD)-based ones (18.3%), with enhanced stability.

Short-Step Synthesized Dopant-Free Spiro-Type Hole-Transporting Materials for Efficient and Stable Perovskite Solar Cells

“…The spiro-type HTMs are widely used because of the merits of spiro-linked architectures, which include a nonplanar 3D geometry, high T g , and good solubility because of weak intermolecular π–π interactions. , Therefore, as a synthetic approach, we decided to use the core structure of the basic symmetric spirobifluorene without changing it to take advantage of its structure. Recently, our group reported a dopant-free spiro-type HTM for PSCs. , The PSCs with our reported HTMs demonstrated greater thermal stability than those with both doped and nondoped Spiro-OMeTAD . These HTMs have both strong electron-donating N , N -alkylamino and electron-withdrawing cyano groups.…”

“…In each synthesis route for SF67 and SF71 , the Buchwald–Hartwig amination reaction was performed twice according to the reported method . Moreover, the synthesis of SF67 and SF71 was easier than the syntheses of our reported HTMs having a cyano substituent , because commercially available materials can be used as starting materials. Thus, the advantages of SF67 and SF71 are that they are easier to synthesize than our previously reported HTMs.…”

“…Recently, our group reported a dopant-free spiro-type HTM for PSCs. 39,40 The PSCs with our reported HTMs demonstrated greater thermal stability than those with both doped and nondoped Spiro-OMeTAD. These HTMs have both strong electrondonating N,N-alkylamino and electron-withdrawing cyano groups.…”

Defect suppression of a perovskite film with In2O3 quantum dots for improved solar cell performance

“…[1][2][3] Among them, organometallic halide perovskites (OHPs) have drawn much attention to rival the photovoltaic fields. [4][5][6][7] Taking advantage of the optoelectronic superiorities of perovskites, researchers have increased the efficiency of perovskite solar cells (PSCs) from about 3% to 25.7% in recent years. [8][9][10] Besides, owing to the solutionprocessable, low-cost, 11,12) and large-area manufacturable advantages, perovskites have also obtained more and more investment from industrialization and commercialization fields.…”