Achieving Highly Efficient Nonfullerene Organic Solar Cells with Improved Intermolecular Interaction and Open-Circuit Voltage.

Huifeng Yao,Han Young Woo,Long Ye,Junxian Hou,Runnan Yu,Jianhui Hou,Gregory M Su,Hao Zhang,Bomee Jang,Guangchao Han,Harald Ade,Bowei Gao,Cheng Wang,Yuanping Yi,Yong Cui

doi:10.1002/adma.201700254

Abstract

A new acceptor-donor-acceptor-structured nonfullerene acceptor ITCC (3,9-bis(4-(1,1-dicyanomethylene)-3-methylene-2-oxo-cyclopenta[b]thiophen)-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d':2,3-d']-s-indaceno[1,2-b:5,6-b']-dithiophene) is designed and synthesized via simple end-group modification. ITCC shows improved electron-transport properties and a high-lying lowest unoccupied molecular orbital level. A power conversion efficiency of 11.4% with an impressive V OC of over 1 V is recorded in photovoltaic devices, suggesting that ITCC has great potential for applications in tandem organic solar cells.

Highlights

Organic solar cells (OSCs) with bulk heterojunction (BHJ) structures consisting of electron-donor and electron-acceptor materials have achieved impressive progress over the past decade,[1, 2] demonstrating their great potential in practical applications
Considerable efforts have been devoted to developing efficient molecular design strategies to optimize polymer or small-molecule (SM) electron donors,[4,5,6,7] with power conversion efficiencies (PCEs) of OSC devices based on fullerenes having surpassed 11%.[8]
Many non-fullerene electron acceptors based on naphthalene diimide (NDI),[18] perylene diimide (PDI),[14, 19,20,21,22,23,24,25] or indacenodithiophene (IDT)[13, 15, 26,27,28,29] units as core structures have been designed and applied to OSCs

Summary

Introduction

R. China Keywords: organic solar cells, non-fullerene acceptor, end-group modification, intermolecular π–π stacking, molecular energy level Compared to ITIC (Egopt = 1.59 eV) thin films, the blue-shifted absorption spectrum of ITCC thin films (Figure 2a) can be attributed to the decreased intermolecular charge transfer (ICT) due to the more electron-donating thiophene units relative to benzene units, and less solar photons will be absorbed for the corresponding OSC devices.

Results

Conclusion