Side-Chain Engineering of Donor-Acceptor Conjugated Small Molecules As Dopant-Free Hole-Transport Materials for Efficient Normal Planar Perovskite Solar Cells

ACS Appl Mater Interfaces. 2019 Dec 26;11(51):48556-48563. doi: 10.1021/acsami.9b17386. Epub 2019 Dec 16.


Simultaneously improving efficiency and stability, which are particularly crucial factors for the commercialization of perovskite solar cells (PSCs), remains a major challenge. For high-efficiency normal PSCs, the development of stable dopant-free hole-transport materials (HTMs) seems imperative. Here, we developed potential donor-acceptor small molecules (BTTI) as HTMs for normal planar PSCs. Through tailoring its alkyl side-chain length as BTTI-C6, BTTI-C8, and BTTI-C12, our results show that upon shortening the side chain of BTTI, the hole mobility, film-forming capability, and resultant device performance were remarkably improved, with the device conversion efficiencies of 19.69% for BTTI-C6, 18.89% for BTTI-C8, and 17.49% for BTTI-C12. Meanwhile, compared to those made with the routine doped Spiro-OMeTAD, devices based on our dopant-free HTMs exhibited significantly improved stability. This work paves the way to the development of effective dopant-free HTMs for high-performance PSCs.

Keywords: donor−acceptor conjugated small molecules; dopant-free; hole-transport materials; perovskite solar cells; side-chain engineering.