Active Layer Materials for Organic Solar Cells - Organic Solar Cells: Materials and Device Physics - page 17

Chapter 2
Active Layer Materials for Organic
Solar Cells
Jianhui Hou and Xia Guo
Abstract Organic photovoltaic cell (OPV) has emerged as a new competitor to
inorganic material-based solar cells, due to its potential application in large area,
printable, and flexible solar panels. In particular, OPV cells with bulk hetero-
junction architecture (BHJ), in which the photoactive layer consists of a bicon-
tinuous blend of an electron donor and an electron acceptor, has allowed power
conversion efficiencies (PCEs) over 8 %. Electron donor and electron acceptor
materials, with ideal properties are requisite for reaching high PCE. In this chapter,
the relationship between molecular structure and photovoltaic property of active
layer materials will be discussed, and also the rules of molecular design of organic
photovoltaic materials will be presented. Furthermore, the latest progresses of
electron donors and electron acceptors, especially for conjugated polymers and the
fullerene derivatives, will be introduced.
2.1 Introduction
An Organic photovoltaic cell (OPV) cell is composed of a film of organic pho-
tovoltaic active layer, sandwiched between a transparent electrode and a metal
electrode. As a successful branch of OPV, polymer solar cells (PSCs) have
attracted much attention. Typically, the active layer PSC device is composed of a
blend film of conjugated polymer (as electron donor) and a small molecular
acceptor. The conjugated polymer donor and the fullerene derivative acceptor are