In perovskite solar cells (PSCs)

it is important to construct electron transport layer (ETL) with ideal surface morphology and advantageous electron transport dynamics. In this work

a functional TiO

2

ETL is designed and constructed based on a novel Ti

3+

self-doping strategy. Experimental results indicate that Ti

3+

dopant can optimize TiO

2

film crystallization process by facilitating the assembly of precursor particles

reducing the content of pore-forming reagent

and enhancing the adhesion of precursors to glass substrate in film formation process. Therefore

the modified surface morphology inhibits the formation of undesired hole structure. Besides

self-doping moderately generates oxygen vacancies on TiO

2

surface and a shallower TiO

2

Fermi energy level. These not only result in a stronger interfacial electronic coupling

but also establish an advantageous energy band alignment. These merits optimize interfacial electron transfer dynamics by inhibiting recombination loss and facilitating electron extraction. Benefiting from the optimized TiO

2

ETL

hole transport layer (HTL)-free carbon electrode based CsPbI

3

PSCs deliver a high efficiency of 18.62%

representing one of the highest levels in this field.