Organic photovoltaics (OPVs) have progressed steadily through three stages of photoactive materials development: (i) use of poly­(3-hexylthiophene) and fullerene-based acceptors (FAs) for optimizing bulk heterojunctions; (ii) development of new donors to better match with FAs; (iii) development of non-fullerene acceptors (NFAs). The development and application of NFAs with an A–D–A configuration (where A = acceptor and D = donor) has enabled devices to have efficient charge generation and small energy losses (E loss < 0.6 eV), resulting in substantially higher power conversion efficiencies (PCEs) than FA-based devices. The discovery of Y6-type acceptors (Y6 = 2,2′-((2Z,2′Z)-((12,13-bis­(2-ethylhexyl)-3,9-diundecyl-12,13-dihydro-[1,2,5]-thiadiazolo­[3,4-e]-thieno­[2″,3″:4′,5′]­thieno-[2′,3′:4,5]­pyrrolo-[3,2-g]­thieno-[2′,3′:4,5]­thieno-[3,2-b]­indole-2,10-diyl)­bis­(methanylylidene))­bis­(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))­dimalononitrile) with an A–DA′ D–A configuration has further propelled the PCEs to go beyond 15% due to smaller E loss values (∼0.5 eV) and higher external quantum efficiencies. Subsequently, the PCEs of Y6-series single-junction devices have increased to >19% and may soon approach 20%. This review provides an update of recent progress of OPV in the following aspects: developments of novel NFAs and donors, understanding of the structure–property relationships and underlying mechanisms of state-of-the-art OPVs, and tasks underpinning the commercialization of OPVs, such as device stability, module development, potential applications, and high-throughput manufacturing. Finally, an outlook and prospects section summarizes the remaining challenges for the further development of OPV technology.

Light induced fullerene dimerization is controlled by both the fullerene and polymer morphology of organic solar cells.

The technology behind a large area array of flexible solar cells with a unique design and semitransparent blue appearance is presented. These modules are implemented in a solar tree installation at the German pavilion in the EXPO2015 in Milan/IT. The modules show power conversion efficiencies of 4.5% and are produced exclusively using standard printing techniques for large‐scale production.

Increasing the lifetime of polymer based organic solar cells is still a major challenge. Here, the photostability of bulk heterojunction solar cells based on the polymer poly[4,4′-bis(2-ethylhexyl)dithieno[3,2-b:2′,3′-d]silole)-2,6-diyl-alt -[2,5-bis(3-tetradecylthiophen-2-yl)thiazole[5,4-d]thiazole)-1,8-diyl] (PDTSTzTz) and the fullerene [6,6]-phenyl-C 61 -butyric acid methyl ester (PC 60 BM) under inert atmosphere is investigated. Correlation of electrical measurements on complete devices and UV-vis absorption measurements as well as highperformance liquid chromatography (HPLC) analysis on the active materials reveals that photodimerization of PC 60 BM is responsible for the observed degradation. Simulation of the electrical device parameters shows that this dimerization results in a signifi cant reduction of the charge carrier mobility. Both the dimerization and the associated device performance loss turn out to be reversible upon annealing. BisPC 60 BM, the bis-substituted analog of PC 60 BM, is shown to be resistant towards light exposure, which in turn enables the manufacture of photostable PDTSTzTz:bisPC 60 BM solar cells.

The photo-oxidation behavior of three different polymersnamely, poly(3-hexylthiophene) (P3HT), poly[2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b′]dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (C-PCPDTBT), and poly[2,6-(4,4-bis(2-ethylhexyl)dithieno[3,2-b:2′,3′-d]silole)-alt-4,7-(2,1,3-benzothiadiazole)] (Si-PCPDTBT)is investigated in neat polymer films and in blends with [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) for different polymer:PCBM ratios. PCBM is shown to have both stabilizing and destabilizing effects, the extent of which is dependent on the type of polymer with which it is blended. Screening of the polymer from incident light by PCBM turns out to play an only minor role in the stabilization of P3HT. Quenching of the polymer excited states is also not a significant stabilization mechanism, as demonstrated by the comparison of the reduction of photo-oxidation rates to the extent of photoluminescence quenching by PCBM and 2,7-dinitrofluorenone (DNF). Photoinduced absorption spectroscopy reveals that the enhanced degradation of C-PCPDTBT in blend films with PCBM correlates with the population of the polymer triplet state via the polymer:PCBM charge-transfer state.

the worldwide peak capacity of solar energy production has caught up with wind power, and is expected to be the first renewable energy to exceed the TWp limit in the next few years, probably already by 2023. [1] Solar Power Europe reports levelized cost of electricity (LCOE) for photovoltaic power to range from 5 c (kWh) −1 in the North of Europe like in Helsinki and 3 c (kWh) −1 in the south of Europe, like in Malaga, which will further go down to 3 c (kWh) −1 respectively 1c (kWh) −1. [2] Fraunhofer ISE reports in the 2019 PV report that photovoltaic installations are dominated by crystalline silicon (c-Si) with a market share of over 95% in solar farms and on rooftops. [3] With the rise of the solar power century, photovoltaic applications and installations will go beyond the traditional green field power plants and enter every aspect of our daily life. Urban, naval and space mobility, residential buildings and business towers, all types of facades, portable and Internet of Things (IoT) applications, clothing-almost any aspect of our life can and will be powered by solar energy. While c-Si appears untouchable as leading PV main stream technology for a longer time, many of the new applications which rely on flexibility, transparency, color management, integrability or simply elegant appearance require novel photovoltaic materials and technologies.

This roadmap includes the perspectives and visions of leading researchers in the key areas of flexible and printable electronics. The covered topics are broadly organized by the device technologies (sections 1-9), fabrication techniques (sections 10-12), and design and modeling

During the last years, the development of new active materials has led to constant improvement in the power conversion efficiency (PCE) of solution‐processed organic photovoltaics (OPV) to nowadays record values above 17% on small lab cells. In this work, we show the developments and results of a successful upscaling of such highly efficient OPV systems to the module level on large areas, which yielded two new certified world record efficiencies, namely, 12.6% on a module area of 26 cm2 and 11.7% on a module area of 204 cm2. The decisive developments leading to this achievement include the optimization of the module layout as well as the high‐resolution short‐pulse (nanosecond) laser structuring processes involved in the manufacturing of such modules. By minimizing the inactive areas within the total module area that are used for interconnecting the individual solar cells of the module in series, geometric fill factors of over 95% have been achieved. A production yield of 100% working modules during the manufacturing of these modules and an extremely narrow distribution of the final PCE values underline the excellent process control and reproducibility of the results. The new developments and their implementation into the production process of the record OPV modules are described in detail, along with the challenges that arose during this development. Finally, dark lock‐in thermography (DLIT), electroluminescence (EL), and photoluminescence (PL) measurements of the record module are presented.