Dopant‐Free Spiro‐Triphenylamine/Fluorene as Hole‐Transporting Material for Perovskite Solar Cells with Enhanced Efficiency and Stability

Abstract

Chemical doping is often used to enhance electric conductivity of the conjugated molecule as hole‐transporting material (HTM) for the application in optoelectronics. However, chemical dopants can promote ion migration at the electrical field, which deteriorates the device efficiency as well as increases the fabrication cost. Here, two star HTMs, namely 2,2′,7,7′‐tetrakis(N,N‐di‐p‐methoxyphenyl‐amine) 9,9′‐spirobifluorene (Spiro‐OMeTAD) and poly(triarylamine) are subjeted to chemical combination to yield dopant‐free N2,N2,N2′,N2′,N7,N7,N7′,N7′‐octakis(4‐methoxyphenyl)‐10‐phenyl‐10H‐spiro[acridine‐9,9′‐fluorene]‐2,2′,7,7′‐tetraamine (SAF‐OMe). The power conversion efficiencies (PCEs) of 12.39% achieved by solar cells based on pristine, dopant‐free SAF‐OMe are among the highest reported for perovskite solar cells and are even comparable to devices based on chemically doped Spiro‐OMeTAD (14.84%). Moreover, using a HTM comprised of SAF‐OMe with an additional dopant results in a record PCE of 16.73%. Compared to Spiro‐OMeTAD‐based devices, SAF‐OMe significantly improves stability.

High-performance flexible and air-stable perovskite solar cells with a large active area based on poly(3-hexylthiophene) nanofibrils

“…36,46 The LN-P3HT effectively blocked the penetration of oxygen and water molecules into the perovskite; hence, the exible LN-P3HT devices stored under ambient conditions (relative humidity: 30%) for 30 days exhibited a more stable performance than the exible LP-P3HT device. [47][48][49] Fig . 7A).…”

Two-dimensional organic-inorganic hybrid perovskite: from material properties to device applications

“…However, the Achilles heel of PeSCs is their stability resisting high temperature, illumination and humidity. Through ETL or HTL property improvement [82][83][84][85][86], interfaces engineering [87][88][89] and active layer modification [90], the device stability can be improved. Utilizing 2D perovskite as the photoactive layer offers a strategy for stable solar cells with simple spin-coating process.…”

Facilely Synthesized spiro[fluorene‐9,9′‐phenanthren‐10′‐one] in Donor–Acceptor–Donor Hole‐Transporting Materials for Perovskite Solar Cells

“…[1] PSCs have since achieved rapid increase in PCE from 3.8 %t oo ver 20 %, [2][3][4][5][6] owing to the perovskite active layer,w hich exhibits severalb enefits like broad absorptivity, long electron-hole diffusion length, [7] efficient charge-transport capability, [8][9][10] and low charge-recombination rate. [44,45] Considerable efforts have also been devoted to investigating suitable HTMs by replacing the spiro-based core with novel spiro-based HTMs like spiro-acridine-fluorene, [46,47] spiro-bi[thieno [3,4-b] [1,4]dioxepine], [48] dispiro-oxepine, [49] spiro[fluorene-9,9'-xanthene], [6,[50][51][52][53] and spiro-phenylpyrazole-fluorine. [2,3,5] As Spiro-OMeTAD exhibits al ow recombination rate and efficient hole-transport mobility,t he overall devicep erformance is improved when the materiali si ncluded.…”