Vertical TiO₂ Nanorods as a Medium for Stable and High-Efficiency Perovskite Solar Modules

Abstract

Perovskite solar cells employing CH3NH3PbI3-xClx active layers show power conversion efficiency (PCE) as high as 20% in single cells and 13% in large area modules. However, their operational stability has often been limited due to degradation of the CH3NH3PbI3-xClx active layer. Here, we report a perovskite solar module (PSM, best and av. PCE 10.5 and 8.1%), employing solution-grown TiO2 nanorods (NRs) as the electron transport layer, which showed an increase in performance (∼5%) even after shelf-life investigation for 2500 h. A crucial issue on the module fabrication was the patterning of the TiO2 NRs, which was solved by interfacial engineering during the growth process and using an optimized laser pulse for patterning. A shelf-life comparison with PSMs built on TiO2 nanoparticles (NPs, best and av. PCE 7.9 and 5.5%) of similar thickness and on a compact TiO2 layer (CL, best and av. PCE 5.8 and 4.9%) shows, in contrast to that observed for NR PSMs, that PCE in NPs and CL PSMs dropped by ∼50 and ∼90%, respectively. This is due to the fact that the CH3NH3PbI3-xClx active layer shows superior phase stability when incorporated in devices with TiO2 NR scaffolds.

Research Update: Large-area deposition, coating, printing, and processing techniques for the upscaling of perovskite solar cell technology

“…22 Whereas most layers have been ablated by working on the laser wavelengths and parameters, for particularly difficult layers to remove, such as TiO 2 nano-rods, an intermediate thin compact layer of TiO 2 between the TCO and the mesoporous nanorod layer was shown to facilitate the patterning of the latter without damaging the TCO. 51,52 The presence of a TiO 2 scaffold, compared to modules without (i.e., planar), led to improved device stability. 51 Patterning and shaping by means of lasers brings many advantages such as a very high precision, resolution, processing speed, automation, high selectivity, and low cost.…”

“…51,52 The presence of a TiO 2 scaffold, compared to modules without (i.e., planar), led to improved device stability. 51 Patterning and shaping by means of lasers brings many advantages such as a very high precision, resolution, processing speed, automation, high selectivity, and low cost. 11 Laser patterning is able to reduce the dead areas in perovskite based modules, minimizing such areas used for contacts.…”

Carbon Nanotubes in TiO2 Nanofiber Photoelectrodes for High‐Performance Perovskite Solar Cells

“…Since 2009, the PCEs of PSCs have increased from 3.8% to 22.1%, making them the fastest advancing PV technology 6, 7, 8, 9, 10. Recent successful fabrication of flexible and large‐area PSC devices shows great promise for the commercialization of this cutting‐edge PV technology 11, 12, 13, 14, 15, 16…”

Rational design of SnO2-based electron transport layer in mesoscopic perovskite solar cells: more kinetically favorable than traditional double-layer architecture

“…Concerning materials, TiO 2 has been widely adopted in such duallayer structured ETL for M-PSCs so far [8,[12][13][14][15]. Actually, many attempts have been performed in order to make ETL kinetically more favorable, e.g., surface modifications, nanostructure tailoring, and the utilizations of alternative materials with better optoelectronic properties [16][17][18][19][20][21][22][23]. Compared with TiO 2 , SnO 2 is chemically stable as well and, more importantly, its charge mobility is almost two orders of magnitude higher than that of TiO 2 [11,24].…”