Simple, Robust, and Going More Efficient: Recent Advance on Electron Transport Layer‐Free Perovskite Solar Cells

Abstract

Perovskite solar cells (PSCs) have shown great potential for photovoltaic applications with their unprecedented power conversion efficiency advancement. Such devices generally have a complex structure design with high temperature processed TiO2 as the electron transport layer (ETL). Further careful design of device configuration to fully tap the potentials of perovskite materials is expected. Particularly, for the practical application of PSCs, it is crucial to simplify their device structures thus the associated manufacturing process and cost while maintaining their efficiency to be comparable with the conventional devices. But how simple is simple? ETL‐free PSCs promise the simplest structured, thus simple manufacturing processes and low cost large area PSCs in practical applications. They can also help the further exploration of the great potential of perovskite materials and understanding the working principle of PSCs. Within this review, the evolution of the PSC is outlined by discussing the recent advances in the simplification of device configuration and processes for cost effective, highly efficient, and robust PSCs, with a focus on ETL‐free PSCs. Their advancement, key issues, working mechanism, existing problems, and future performance enhancements. This review aims to promote the future development of low cost and robust ETL‐free PSCs toward more efficient power output.

Ionic Liquid Additive‐Assisted Highly Efficient Electron Transport Layer‐Free Perovskite Solar Cells

“…These merits render the possibility to manufacture highperformance PSCs through the industrial continuous production line. The state-of-the-art PSC typically consists of the perovskite layer sandwiched by electron and hole transport layers [6][7][8] or even much more layers to promote the interfacial charge transfer. [9] Regarding industrial manufacturing, the addition of one layer notably increases the difficulties in designing the production line.…”

Charge-Transporting-Layer-Free, Vacuum-Free, All-Inorganic CsPbIBr2 Perovskite Solar Cells Via Dipoles-Adjusted Interface

“…The superior properties of the adjustable band gap, the great light absorption, and the high carrier mobilities promote the perovskite materials to a new star against the backdrop of rapid advancement of science and technology in the photovoltaic society [ 1 , 2 , 3 , 4 ]. Due to the scientists’ continuous efforts, the perovskite solar cells (PSCs) have achieved the power conversion efficiency (PCE) over 25% in the past decade with the opportunities to become a low-cost and industry-scalable technology, which quickly makes PSCs become a serious competitor to other thin-film solar cells [ 2 , 5 , 6 ]. Perovskite has a generic formula ABX 3 , which can be divided into two types as organic-inorganic hybrid or inorganic perovskites.…”

Hydrothermally Treated TiO2 Nanorods as Electron Transport Layer in Planar Perovskite Solar Cells

“…[ 10–12 ] Due to the high transparency with wide bandgap of a TiO 2 semiconductor, [ 13–15 ] it is expected to extract photogenerated electrons and to serve as an efficient hole‐blocking layer in promising PSCs. [ 16–18 ] TiO 2 nanorods (NRs), used as the ETL, have less grain boundaries due to their shape and crystallographic orientation, thus causing an excellent charge collection. [ 19 ] Furthermore, TiO 2 NRs have longer lifetime electrons which contribute to a higher quantity of charge carriers and reduce the amount of electron–hole recombination, consequently leading to an increased PCE.…”