Synergetic passivation of PbS colloidal quantum dots by bulk heterojunction-type interlayers enables >14% solar cell efficiency
Journal
Journal of Materials Chemistry A
Journal Volume
14
Journal Issue
14
Start Page
8161
End Page
8170
ISSN
2050-7488
2050-7496
Date Issued
2026
Author(s)
Cheng, Ching-Hsuan
Wang, Sheng-Fu
Hung, Chieh-Ming
Chen, Bo-Han
Tsai, Ying-Yi
Chu, Ching-Yuan
Lin, Chen-Yu
Ni, I.-Chih
Lo, Chen-Sheng
Yang, Shang-Da
Chen, Hsieh-Chih
Chou, Pi-Tai
Abstract
PbS colloidal quantum dots (CQDs) are promising low-bandgap absorbers for solution-processable photovoltaics, yet their performance is restricted by surface traps that induce nonradiative recombination and suppress the open-circuit voltage (VOC) and fill factor (FF). Conventional ligand treatments only partially reduce trap density, leaving residual defects at buried interfaces. Herein, we report an interfacial engineering strategy using two near-infrared non-fullerene acceptors (NFAs), BTPV-4F and BATPV-4F, incorporated as bulk heterojunction-type hole-transporting layers (BHJ-HTLs) on PbS CQDs. These NFAs possess deep HOMO levels, strong quadrupole moments, and ordered π–π stacking, which enable selective hole extraction and suppress trap-assisted recombination rather than serving as additional light harvesters. The ternary BHJ-HTLs engage in multi-site coordination with PbS surfaces through Pb–S, Pb–F, and Pb–O interactions, while improving molecular ordering and preserving favorable band-edge alignment. Such synergistic interactions suppress interfacial trap states, enhancing carrier extraction and stability. Despite their broad absorption to ∼950 nm, they yield only a modest photocurrent increase. Instead, simultaneous improvements in VOC (0.65 to 0.68 V) and FF (68.1% to 70.94%) dominate efficiency gains, boosting solar efficiencies from 11.99% to 14.02%. This work demonstrates a molecular design strategy that advances efficiency and durability in low-bandgap CQD photovoltaics.
Publisher
Royal Society of Chemistry (RSC)
Type
journal article