Deciphering Electron Interplay at the Fullerene/Sputtered TiO_x Interface: A Barrier-Free Electron Extraction for Organic Solar Cells

Abstract

Organic photovoltaics (OPVs) technology now offers power conversion efficiency (PCE) of over 18% and is one of the main emerging photovoltaic technologies. In such devices, titanium dioxide (TiO x ) has been vastly used as an electron extraction layer, typically showing unwanted charge-extraction barriers and the need for light-soaking. In the present work, using advanced photoemission spectroscopies, we investigate the electronic interplay at the interface between low-temperature-sputtered TiO x and C70 acceptor fullerene molecules. We show that defect states in the band gap of TiO x are quenched by C70 while an interfacial state appears. This new interfacial state is expected to support the favorable energy band alignment observed, showing a perfect match of transport levels, and thus barrier-free extraction of charges, making low-temperature-sputtered TiO x a good candidate for the next generation of organic solar cells.

Carbon Nanostructures Decorated with Titania: Morphological Control and Applications

“…The interface between fullerenes and titania has been deeply investigated. It was recently found that defect states in the band gap of titania are quenched by C 70 while an interfacial state appears, showing a barrier-free extraction of charges (Figure 3) for the next generation of organic solar cells [178]. However, in studies such as this one, fullerenes are added onto preformed titania.…”

Powering internet-of-things from ambient energy: a review

“…Transport layer interface degradation is also well-known, in particular for many new non-fullerene based organic solar cell systems [236,237], for example due to photocatalytic decomposition of these molecules at metal oxide interfaces. This has made studies on transport layer interfaces very relevant for the OPV field [238]. For indoor PV, however, these effects are much less of an issue due to the lack of harsh and alternating weather conditions, and in particular, the different light spectrum and intensity at indoor conditions, i.e.…”

Strategies for high‐performance perovskite solar cells from materials, film engineering to carrier dynamics and photon management

“…Energy levels of different CTMs, where the data are from: SnO 2 , 52 In 2 O 3 , 333 CdSe, 334 Nb 2 O 5 , 331 Fe 2 O 3 , 335 ZnO, 86 SnS 2 , 336 WO 3 , 331 Zn 2 SnO 4 , 337 TiO 2 , 282 TiS 2 , 338 ZnTiO 3 , 331 BaSnO 3 , 337 SrTiO 3 , 333 Bi 2 S 3 , 331 CdS, 331 GaN, 331 PCBM, 55 C 60 , 339 Bis‐C 60 , 339 C 70 , 340 ICBA, 339 PTB7‐Th, 341 Cu 2 O, 337 NiO x , 176 CuO, 337 CuSCN, 342 NiMgLiO, 342 V 2 O 5 , 342 CuI, 342 PCDTBT, 342 Poly(DTSTPF‐r‐BThTPD), 343 PBT, 342 PPP, 342 assy‐PBTBDT, 343 KTM3, 344 X‐QUPD, 342 X‐OTPD, 342 P6CT‐Na, 342 PPN, 342 PTAA, 345 PT, 342 Poly‐TPD, 176 P3HT, 343 Spiro‐OMeTAD, 158 PVB‐DAAF, 342 PEDOT:PSS, 78 and CPE‐K 342 …”

“…Energy levels of different CTMs, where the data are from: SnO 2 , 52 In 2 O 3 , 333 CdSe, 334 333 Bi 2 S 3 , 331 CdS, 331 GaN, 331 PCBM, 55 C 60 , 339 Bis-C 60 , 339 C 70 , 340 ICBA, 339 PTB7-Th, 341 Cu 2 O, 337 NiO x , 176 CuO, 337 CuSCN, 342 NiMgLiO, 342 V 2 O 5 , 342 CuI, 342 PCDTBT, 342 Poly(DTSTPF-r-BThTPD), 343 PBT, 342 PPP, 342 assy-PBTBDT, 343 KTM3, 344 X-QUPD, 342 X-OTPD, 342 P6CT-Na, 342 PPN, 342 PTAA, 345 PT, 342 Poly-TPD, 176 P3HT, 343 Spiro-OMeTAD, 158 PVB-DAAF, 342 PEDOT:PSS, 78 and CPE-K. 342 during the preparation process, which improved the quality of cp-TiO 2 the film with highly uniform and pinhole free and effectively improved the efficiency and stability of (FAPbI 3 ) 0.85 (MAPbBr 3 ) 0.15 HPSC devices. Except for these metal ions, numerous function materials serve as additives to treat the TiO 2 films, such as Na 2 S, 374 TiCl 4 , 375,376 La 2 O 3 , 377 SbI 3 , 378 CsBr, 379 reduced graphene oxide (rGO), 380 C 60 , 381 and tetraethylammonium p-toluenesulfonate (TEATS).…”