• Energy Research

A round robin study across 15 laboratories in China was carried out using single junction devices with an active area of 1 cm(2) and differently sized small module with an active area of 20 and 24 cm(2) respectively. The devices represented the state of the art in terms of processing as they did not employ indium or vacuum and were prepared using only printing and coating techniques on flexible substrates. The devices were studied in their flexible form and thus approach the vision of what the polymer solar cell is. The main purpose of the work was to establish and chart geographic and cultural differences in what constitutes a competent IV-characterization procedure and also to establish the spread in measured data across the globe. The main finding is that efficiency data deviated up to 30% from the mean while an overall relative standard deviation of 12% was observed. Collating this spread with previous findings points toward a seemingly region-independent i.e. global observation of the uncertainty in the /Vcharacterization of a polymer solar cell. Finally, we highlight what might be done to improve the accuracy of the reported data. (C) 2013 Elsevier B.V. All rights reserved.

The non-toxic solvent of N,N-diethylformamide exhibits weak coordination with SnI2, rendering the formation of smoother lead-free perovskite films with larger grain sizes, which facilitates the carrier transport and reduces recombination.

Two donor–acceptor copolymers based on isomeric acceptor units, [7,7′‐bithieno[2′,3′:4,5]thieno[2,3‐d]thieno[3,2‐b]pyridine]‐5,5′(4H,4′H)‐dione (BTTP) and [2,2′‐bithieno[2′,3′:4,5]thieno[2,3‐d]thieno[3,2‐b]pyridine]‐5,5′(4H,4′H)‐dione (iBTTP), are developed to study the effect of isomeric structures on photovoltaic performance. Compared with PBDTBTTP, PBDTiBTTP possesses a smaller bandgap for good light harvesting and a better π–π stacking for higher hole mobility. PBDTiBTTP solar cells present balanced mobilities and good nanoscale phase separation, giving a power conversion efficiency (PCE) of 6.51%, with higher short‐circuit current (Jsc) and fill factor (FF). image

Organ–inorganic hybrid perovskite solar cells (PSCs) have attracted extensive attention with a certified power conversion efficiency (PCE) beyond 25% due to their superior photoelectric properties. However, most reported high‐efficiency PSCs are fabricated with toxic solvents, which raises a major obstacle for potential commercialization. Herein, the recent research progress of green solvents for high‐efficiency PSCs is summarized from antisolvents, precursor solvents, and solvents for electron/hole transport materials, aiming to promote the development of green solvents for PSCs and meet the requirement of sustainable development of the PSCs field. Future challenges and prospects are also discussed to expedite the rational design of green‐solvent‐processed PSCs.

A prebisaddition-confined bisfunctionalization (PCB) approach was designed for the construction of isomer-free fullerene bisadducts for efficient polymer solar cells.

AbstractThe emergence of Y6‐type nonfullerene acceptors has greatly enhanced the power conversion efficiency (PCE) of organic solar cells (OSCs). However, which structural feature is responsible for the excellent photovoltaic performance is still under debate. In this study, two Y6‐like acceptors BDOTP‐1 and BDOTP‐2 were designed. Different from previous Y6‐type acceptors featuring an A–D–Aʹ–D–A structure, BDOTP‐1, and BDOTP‐2 have no electron‐deficient Aʹ fragment in the core unit. Instead, there is an electron‐rich dibenzodioxine fragment in the core. Although this modification leads to a marked change in the molecular dipole moment, electrostatic potential, frontier orbitals, and energy levels, BDOTP acceptors retain similar three‐dimensional packing capability as Y6‐type acceptors due to the similar banana‐shaped molecular configuration. BDOTP acceptors show good performance in OSCs. High PCEs of up to 18.51% (certified 17.9%) are achieved. This study suggests that the banana‐shaped configuration instead of the A–D–Aʹ–D–A structure is likely to be the determining factor in realizing high photovoltaic performance.

AbstractWe modified perovskite/Spiro‐OMeTAD interface by using two novel phosphonium salts containing PF6− counter anion (i.e., ClTPPPF6 and BrTPPPF6). The cation and anion in phosphonium salts possess not only ionic bonds but also coordination bonds with perovskites. The anion and cation vacancies at the surface and GBs of perovskite films can be filled by phosphonium cations and PF6− anions, respectively, resulting in reduced defect density and prolonged carrier lifetimes. The stronger chemical interaction and accordingly better defect passivation were certified for BrTPPPF6 than ClTPPPF6. As a result, the devices modified by ClTPPPF6 and BrTPPPF6 deliver a PCE of 21.73% and 22.15%, respectively, which far exceed 20.6% of the control device. The unsealed BrTPPPF6 modified device maintains 98.2% of its initial efficiency value after thermal aging of 1320 h whereas merely 84.7% for the control device. 96.4% of its original efficiency was retained for BrTPPPF6‐modified device after ambient exposure of 2016 h.image

AbstractImproved efficiency and stability of the organic solar cells (OSCs) are the critical considerations for practical applications. The interface between the interlayer and bulk heterojunction has recently been shown as one of the weak links associated with the degradation in the nonfullerene acceptor (NFA)‐based OSCs. It shows that the removal of the interfacial chemical reactions between the 2‐(3‐oxo‐2,3‐dihydroinden‐1‐ylidene)malononitrile (INCN) moieties in NFA and poly(3,4‐ethylenedioxythiophene)‐polystyrene sulfonate (PEDOT:PSS) hole extraction layer (HEL) is desired for enhancing the device stability. In this work, we show that the use of a bilayer MoO3/antimonene HEL favors the operational stability in OSCs through maintaining a high built‐in potential and suppression of an undesired interfacial reaction between INCN moieties in NFA and the PEDOT structures in PEDOT:PSS. A power conversion efficiency of 16.68% is also obtained for the OSCs with a bilayer MoO3/antimonene HEL, prepared using a blend system of PM6:Y6, demonstrating its suitability for high‐performance OSCs.image

Quantitative relationship between the protective factor (δ) and PCE of stacked structures of OSC with a record PCE of 17.52% is proposed to understand the mechanism and provide a guideline for solvent choices of eco-friendly solvent protection method.