Structure-Property Relationships of Oligothiophene-Isoindigo Polymers for Efficient Bulk-Heterojunction Solar Cells
Artikel i vetenskaplig tidskrift, 2014

A series of alternating oligothiophene (nT)–isoindigo (I) copolymers (PnTI) were synthesized to investigate the influence of the oligothiophene block length on the photovoltaic (PV) properties of PnTI:PCBM bulk-heterojunction blends. Our study indicates that the number of thiophene rings (n) in the repeating unit alters both polymer crystallinity and polymer–fullerene interfacial energetics, which results in a decreasing open-circuit voltage (Voc) of the solar cells with increasing n. The short-circuit current density (Jsc) of P1TI:PCBM devices is limited by the absence of a significant driving force for electron transfer. Instead, blends based on P5TI and P6TI feature large polymer domains, which limit charge generation and thus Jsc. The best PV performance with a power conversion efficiency of up to 6.9% was achieved with devices based on P3TI, where a combination of a favorable morphology and an optimal interfacial energy level offset ensures efficient exciton separation and charge generation. The structure–property relationship demonstrated in this work would be a valuable guideline for the design of high performance polymers with small energy losses during the charge generation process, allowing for the fabrication of efficient solar cells that combine a minimal loss in Voc with a high Jsc.

Författare

Z. F. Ma

Linköpings universitet

Wenjun Sun

Chalmers, Kemi- och bioteknik, Polymerteknologi

Scott Himmelberger

Stanford University

K. Vandewal

Stanford University

Z. Tang

Linköpings universitet

J. Bergqvist

Linköpings universitet

Alberto Salleo

Stanford University

J. W. Andreasen

Danmarks Tekniske Universitet (DTU)

Olle Inganas

Linköpings universitet

Mats Andersson

Chalmers, Kemi- och bioteknik, Polymerteknologi

Christian Müller

Chalmers, Kemi- och bioteknik, Polymerteknologi

Fengling Zhang

Linköpings universitet

Ergang Wang

Chalmers, Kemi- och bioteknik, Polymerteknologi

Energy and Environmental Sciences

1754-5692 (ISSN)

Vol. 7 361-369

Ämneskategorier

Polymerkemi

Materialteknik

Kemiteknik

Materialkemi

Nanoteknik

Energisystem

Kemi

Drivkrafter

Hållbar utveckling

Styrkeområden

Nanovetenskap och nanoteknik

Energi

Materialvetenskap

Infrastruktur

C3SE (Chalmers Centre for Computational Science and Engineering)

DOI

10.1039/C3EE42989J