Dopant‐Free Hole‐Transporting Material with Enhanced Intermolecular Interaction for Efficient and Stable n‐i‐p Perovskite Solar Cells

Abstract

Developing low‐cost, efficient, and stable dopant‐free hole‐transporting materials (HTMs) in perovskite solar cells (PVSCs) is essential to their commercial deployment. Herein, the synthesis of a novel spirofluorene‐dithiolane based small molecular HTM, SFDT‐TDM, through facile and low‐cost synthetic routes is reported. The CH…π interactions in adjacent SFDT‐TDM are beneficial for high hole mobility and the methylthio groups in SFDT‐TDM can serve as Lewis bases to passivate the defects on the surface of perovskite films, leading to suppressed non‐radiative recombination and enhanced charge extraction at the perovskite/HTM interface. As a result, CsxFA1−xPbI3 based PVSCs with SFDT‐TDM as the HTM realize champion power conversion efficiencies (PCEs) of 21.7% and 20.3% for small‐area (0.04 cm2) and large‐area (1.0 cm2) devices with negligible photocurrent hysteresis, respectively. Additionally, all‐inorganic CsPbI3−xBrx based PVSCs with SFDT‐TDM demonstrate an impressive PCE of 17.1% along with excellent stability. This work highlights the great potential of the spirofluorene core for exploring low‐cost and dopant‐free HTMs for PVSCs with high efficiency and stability.

Efficient and Stable 3D/2D Perovskite Solar Cells through Vertical Heterostructures with (BA)4AgBiBr8 Nanosheets

“…[2] It is well known that efficient PVSCs require effective suppression of the nonradiative recombination that often originates from nonideal interface energy alignment as well as defects states. [8][9][10][11][12] Charge-transporting materials modification, surface defects passivation, and dimensional engineering are the most adopted strategies to suppress the nonideal interfacial recombination and reduce the energy losses in PVSCs. [13][14][15][16][17][18][19] Among them, the defects at the grain boundaries of 3D perovskite can act as recombination and trapstate centers for minority carriers, which are always considered detrimental to performance.…”

Efficient and Stable Tin Perovskite Solar Cells by Pyridine‐Functionalized Fullerene with Reduced Interfacial Energy Loss

“…The reduced hole/electron trap densities demonstrate that the defects at the perovskite/ETL interface have been suppressed due to the modification of C 60 -BPy. [48,49] Figure 2g,h displays the steady-state photoluminescence (PL) and time-resolved photoluminescence (TRPL), to further study the charge carrier kinetics at the perovskite/ETL interface (with a structure of glass/perovskite/C 60 ). The C 60 -BPy treated perovskite film shows an obviously decreased intensity compared to the control film.…”

“…The reduced hole/electron trap densities demonstrate that the defects at the perovskite/ETL interface have been suppressed due to the modification of C 60 ‐BPy. [ 48,49 ]…”

Tailored Polymeric Hole‐Transporting Materials Inducing High‐Quality Crystallization of Perovskite for Efficient Inverted Photovoltaic Devices

“…In addition, due to the use of precious metal catalysts in the synthesis process, most of polymeric HTMs are difficult to achieve truly low-cost. [23][24][25][26][27][28][29][30][31][32][33] Another main problem is the high hydrophobicity of PTAA with about 80-100° contact angle, as compared with the traditional wetting HTM-PEDOT:PSS (≈10°). [34] The no-wetting surface of PTAA shows less affinity with polar perovskite precursor solutions, and the poor film coverage during spin-coating leads to inferior device reproducibility.…”