Efficient and low-temperature processed perovskite solar cells based on a cross-linkable hybrid interlayer

Abstract

A cross-linkable conjugated polymer, poly [9,9-bis(6′-(N,N-diethylamino)propyl)-fluorenealt-9,9-bis-(3-ethyl(oxetane-3-ethyloxy)-hexyl)-fluorene (PFN-OX), was investigated as the ntype interface layer for highly efficient and low-temperature processed planar heterojunction perovskite solar cells. Hybrid composite films consisting of PFN-OX and ZnO nanoparticles were utilized as the electron selective layers, and a remarkable power conversion efficiency over 16% was achieved. The cross-linkable PFN-OX provided a robust hybrid composite electron selective layer, which is solvent-resistant during the device fabrication process and results in efficient electron extraction and hole-blocking. Meanwhile, the time-resolved photoluminescence quenching measurements indicated that the charge separation and collection processes were improved for the devices based on PFN-OX:ZnO, in comparison with the devices using pure PFN-OX or ZnO. Device stability and the hysteresis effect were also discussed. Moreover, this study introduces the cross-linking concept in the perovskite solar cells, which will potentially be an effective strategy for high performance perovskite solar cells.4 coefficient, small exciton binding energy, high mobilities of carriers and long exciton diffusion length. 6,21,22,23 These advances have ensured the superior photovoltaic performance for the hybrid perovskites solar cells.In addition to the mesoporous PSSCs, the planar heterojuncton PSSCs 24 have also been developed, which have the advantage of low-temperature process and is suitable for the flexible substrates. 25,26 The planar heterojunction PSSC devices possess the layered architecture, which consists of multiple functional films sandwiched between anode and cathode. These functional films include the electron selective contacts (ESCs), perovskite absorber layer, and hole selective contacts (HSCs). 27 In order to achieve high device performance, various approaches have been conducted. For example, morphology control of the perovskite film 28,29 and the optimization of hole-conducting materials 30,31 have been extensively studied to optimize the device performance. Moreover, intensive efforts have also been made for interface engineering at the electron selective contacts. This provides an effective strategy to enhance the electron collection, leading to the improved device performance. The most commonly used ESC for planar heterojunction PSSCs is based on the titanium oxide (TiOx) materials. 32,33 Several other attempts, include the TiO2/graphene nanocomposites, 34 ZnO nanoparticles 35 and the ultrathin graphene quantum dots 36 were reported as the low-temperature processed ESCs and considerable device efficiencies of over 15% were achieved. Moreover, the surface modification strategy has also been demonstrated to achieve the n-type contact between the active layer and the electrode. 37,38,39 By modifying the surface energy of ITO substrate with Cs2CO3, a device efficiency exceeding 15% was achieved. 37 Most recently, a hybrid n-type contact consisti...

Fast-growing procedure for perovskite films in planar heterojunction perovskite solar cells

“…This is in consistent with the conclusion drawn from the SEM image. Generally, it is believed that methylamine lead halide perovskites are not stable at high temperature over 150 °C [12,24,25]. The perovskite layer may be decomposed to PbI 2 due to the high temperature.…”

Magnesium‐doped Zinc Oxide as Electron Selective Contact Layers for Efficient Perovskite Solar Cells

“…Initially,P SCs were fabricatedw ith am esoporousT iO 2 scaffold as the ESL. [26][27][28][29] However,t he study of ZnO-based ternary oxides as ESLs forP SCs holds ar are record. [22][23][24] Among these metal oxide ESLs, ZnO is particularly promising owing to its high transparency,suitable work function, high electron mobility,a nd structural tailorability at an anoscale level.…”

Low‐Temperature Modification of ZnO Nanoparticles Film for Electron‐Transport Layers in Perovskite Solar Cells

“…To improve the electron‐transport properties, Hu et al. mixed a cross‐linkable conjugated polymer such as poly[9,9‐bis(60‐( N , N ‐diethylamino)propyl)‐fluorene‐alt‐9,9‐bis‐(3‐ethyl(oxetane‐3‐ethyloxy)‐hexyl)‐fluorene] (PFN‐OX) with ZnO nanoparticles …”