Towards high-performance DPP-based sensitizers for DSC applications

A novel, asymmetric DPP bridge/core was synthesized and tested in DSC devices. By desymmetrising the DPP core/bridge, a remarkable IPCE of >80% and a maximum power conversion efficiency of 7.7% were achieved. With the use of a wide-bandgap co-sensitizer, 8.6% PCE was realized under standard AM1.5G sunlight

A highly hindered bithiophene-functionalized dispiro-oxepine derivative as an efficient hole transporting material for perovskite solar cells

Dimethoxydiphenylamine-substituted dispiro-oxepine derivative 2,2′,7,7′-tetrakis-(N,N′-di-4-methoxyphenylamine)dispiro-[fluorene-9,4′-dithieno[3,2-c:2′,3′-e]oxepine-6′,9′′-fluorene] (DDOF) has been designed and synthesized using a facile synthetic route. The novel hole transporting material (HTM) was fully characterized and tested in perovskite solar cells exhibiting a remarkable power conversion efficiency of 19.4%. More importantly, compared with spiro-OMeTAD-based devices, DDOF shows significantly improved stability. The comparatively comprehensive solid structure study is attempted to disclose the common features of good performance HTMs. These achievements clearly demonstrated that the highly hindered DDOF can be an effective HTM for the fabrication of efficient perovskite solar cells and further enlightened the rule of new HTM's design

A structural study of DPP-based sensitizers for DSC applications

Four D-pi-A sensitizers comprising a thienyl-diketopyrrolopyrrole (ThDPP) bridge were synthesized and tested in iodide/triiodide liquid electrolyte DSC devices. The dye series was strategically designed to develop a structure-property relationship. The best performing sensitizer utilized a phenyl-based anchor and triphenylamine donor (eta = 5.03%)

Carbazole-based enamine: Low-cost and efficient hole transporting material for perovskite solar cells

A simple carbazole-based conjugated enamine V950 was synthesized, fully characterized and incorporated into a perovskite solar cell, which displayed high power conversion efficiency close to 18%. The investigated hole transporting material was synthesized via an extremely simple route (one step, no expensive catalysts, no column chromatography or sublimation purification) from commercially available and relatively inexpensive starting reagents, resulting in more than one order of magnitude lower cost of the final product compared to the commercial 2,2′,7,7′-tetrakis(N,N-di-p-methoxy-phenylamine)-9-9′-spirobifluorene (spiro-OMeTAD). This material promises to be a viable p-type organic charge conductor to be employed in the scale-up and manufacturing of perovskite solar modules

Donor- π-donor type hole transporting materials: marked π-bridge effects on optoelectronic properties, solid-state structure, and perovskite solar cell efficiency

Donor-pi-bridge-donor type oligomers (D-pi-D) have been studied intensively as active materials for organic optoelectronic devices. In this study, we introduce three new D-pi-D type organic semiconductors incorporating thiophene or thienothiophene with two electron-rich TPA units, which can be easily synthesized from commercially available materials. A thorough comparison of their optoelectronic and structural properties was conducted, revealing the strong influence of the extent of longitudinal pi-bridge conjugation on both the solid structure of the organic semiconductive materials and their photovoltaic performance when applied as hole transporting materials (HTM) in perovskite solar cells. Single-crystal measurements and time-resolved photoluminescence (TRPL) studies indicate that these coplanar donor-pi-donor type HTMs could be promising alternatives to state-of-the-art spiro-OMeTAD, due to the multiple intermolecular short contacts as charge transporting channels and efficient charge extraction properties from the perovskite layer. The optimized devices with PEH-9 exhibited an impressive PCE of 16.9% under standard global AM 1.5 illumination with minimized hysteretic behaviour, which is comparable to that of devices using spiro-OMeTAD under similar conditions. Ambient stability after 400 h revealed that 93% of the energy conversion efficiency was retained for PEH-9, indicating that the devices had good long-term stability