25th Anniversary Article: A Decade of Organic/Polymeric Photovoltaic Research

Abstract

Organic photovoltaic (OPV) technology has been developed and improved from a fancy concept with less than 1% power conversion efficiency (PCE) to over 10% PCE, particularly through the efforts in the last decade. The significant progress is the result of multidisciplinary research ranging from chemistry, material science, physics, and engineering. These efforts include the design and synthesis of novel compounds, understanding and controlling the film morphology, elucidating the device mechanisms, developing new device architectures, and improving large-scale manufacture. All of these achievements catalyzed the rapid growth of the OPV technology. This review article takes a retrospective look at the research and development of OPV, and focuses on recent advances of solution-processed materials and devices during the last decade, particular the polymer version of the materials and devices. The work in this field is exciting and OPV technology is a promising candidate for future thin film solar cells.

Light Manipulation in Organic Photovoltaics

“…Organic photovoltaic (OPV) cell is a promising technology for clean and renewable energy sources, because it may economically allow the conversion of solar power to electricity with the manufacturing of lightweight, large area, and mechanically flexible solar panels through roll‐to‐roll printing technique 1, 2, 3, 4. Starting from the pioneered bilayer heterojunction OPV,5 much effort has been made toward improving the power conversion efficiency (PCE) of both small molecule and polymer based cells 6, 7, 8, 9, 10, 11, 12.…”

Development of donor–acceptor copolymers based on dioxocycloalkene-annelated thiophenes as acceptor units for organic photovoltaic materials

“…Organic photovoltaics (OPVs) have attracted considerable attention in both academia and industry because of their advantages compared with solar cells based on inorganic materials, including their low weight, flexibility, low cost and ease of processing. 1,2 It has been well established that the active layer of OPVs is typically composed of a blend of a π-conjugated polymer as an electron donor (p-type) and a fullerene derivative as an electron acceptor (n-type), and these materials form an interpenetrating bulk-heterojunction (BHJ) structure to maximize the internal donor-acceptor (D-A) interfacial area for efficient photoinduced charge separation. [3][4][5] To increase the power conversion efficiencies (PCEs), with regard to the electronic structure design, p-type materials must have the following properties: (1) a low optical band gap to broaden the absorption range of solar light, which contributes to an increase in the short-circuit current (J SC ), and (2) a low-lying highest occupied molecular orbital (HOMO) energy level to increase the open-circuit voltage (V OC ), which depends on the difference between the HOMO energy level of the p-type material and the energy level of the lowest unoccupied molecular orbital (LUMO) of the n-type material.…”

“…6,7 In this context, a variety of π-conjugated electron-rich components represented by dithieno [3,2- 9 have been developed and utilized as donor units in D-A copolymers. On the other hand, the development of new acceptor units is still vital for synthesizing D-A copolymers because effective acceptor units are limited to 2,1,3-benzothiadiazole, 8 diketopyrrolopyrrole, 10 thieno [3,4-c]pyrole-4, 6-dione, 11 thieno [3,4-b]thiophene with electron-withdrawing substitutents 12 and naphtho[1,2-c:5,6-c']bis [1,2,5]thiadiazole. 13 We have investigated the development of new electron-accepting materials for n-channel organic field-effect transistors (OFETs) and have applied the developed electron-deficient units to D-A copolymers for OPVs.…”

Understanding the Impact of Hierarchical Nanostructure in Ternary Organic Solar Cells

“…To obtain higher power conversion efficiencies (PCEs), researchers focused on developing new materials with suitable energy levels and high carrier mobilities, optimizing the morphological characteristics of active layers, utilizing various interfacial modifications, and developing new device architectures 5, 6, 7, 8, 9, 10, 11, 12, 13, 14. Currently developed PCEs exceed 10% in single‐junction OSCs 15, 16.…”