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Weak Makes It Powerful: The Role of Cognate Small Molecules as an Alloy Donor in 2D/1A Ternary Fullerene Solar Cells for Finely Tuned Hierarchical Morphology in Thick Active Layers
Author(s) -
Fan Qunping,
Liu Tao,
Zhang Ming,
Su Wenyan,
MéndezRomero Ulises A.,
Yang Tao,
Geng Xinjian,
Hou Lintao,
Yu Donghong,
Liu Feng,
Yan He,
Wang Ergang
Publication year - 2020
Publication title -
small methods
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.66
H-Index - 46
ISSN - 2366-9608
DOI - 10.1002/smtd.201900766
Subject(s) - ternary operation , crystallinity , materials science , alloy , fullerene , open circuit voltage , energy conversion efficiency , chemistry , optoelectronics , voltage , organic chemistry , composite material , computer science , programming language , physics , quantum mechanics
Herein, a novel small molecule donor is first developed, FSM6, which is a cognate molecule to BTR possessing similar molecular structure with comparable optical absorption but different crystallinity. The efficient fullerene‐type ternary small molecular solar cells (SMSCs) based on an alloy donor of BTR and FSM6 in a thick film of 250 nm reveal the improved hierarchical phase separation morphology and molecular structural order of ternary active layers with improved crystallinity of the key donor component BTR. Furthermore, FSM6 as the key third component also plays a role of charge transfer accelerator in ternary SMSCs. As a result, the optimal ternary SMSCs based on BTR:FSM6:PC 71 BM achieve a high power conversion efficiency (PCE) up to 10.21% with the synergistically improved open‐circuit voltage of 0.950 V, short‐circuit current density of 13.85 mA cm −2 , and fill factor of 77.6%, in comparison with either the binary SMSCs of BTR:PC 71 BM (PCE = 9.37%) or FSM6:PC 71 BM (PCE = 8.00%). This work provides a promising methodology to optimize device morphology for high‐performance ternary SMSCs by combining two cognate small molecules with similar absorption spectra but different crystallinity as an alloy donor.