A
schematic of ultrafast interfacial excitons dynamics in the P51:PC71BM blend
after photoexcitation. Credit: SIOM.
Recently,
researchers from the Shanghai Institute of Optics and Fine Mechanics of the
Chinese Academy of Sciences (CAS) have made progress in ultrafast dynamics of
polymer solar cells (PSCs) with Soochow University.
The
research team used femtosecond transient absorption technology to study active
layer of organic solar cells, explaining the contribution of 1,8-diiodooctane
(DIO) additives to the efficiency enhancement of PSCs. The results have been
published in Nanomaterials.
As a new
type of solar cell device, PSCs have the advantages of light weight, mechanical
flexibility and low-cost fabrication. But low efficiency is the main limit of
its large-scale application.
The research
team studied the effect of DIO additives on photocarrier generation in donor
materials (P51) and bulk heterojunction films (P51:PC71BM) by pump-probe
measurement.
They found
that the introduction of DIO additives could improve the lifetime of polaron
pairs in P51, which was beneficial to the photocarrier generation. Moreover, in
bulk heterojunction films (P51:PC71BM), DIO additives could promote free charge
generation as well as charge transfer excitons generation and separation.
From the
aspect of ultrafast dynamics, these results reveal the effect of DIO on carrier
generation and separation, providing an effective route to improve the
efficiency of nanoscale polymer solar cells.