Vacuum‐Free and Solvent‐Free Deposition of Electrodes for Roll‐to‐Roll Fabricated Perovskite Solar Cells

Abstract

Perovskite solar cells (PSCs) are attracting widespread attention due to their exceptional photovoltaic performance and their potential for large‐scale production via low‐cost, high‐throughput roll‐to‐roll (R2R) methods. Full realization of this production approach requires replacement of the evaporated metal electrode commonly used in PSCs. Here, a novel vacuum‐free R2R‐compatible method is introduced to fabricate and deposit printed electrodes based on electrically conductive pastes, which avoids potential loss of PSC performance due to solvent migration from the pastes. Flexible R2R‐fabricated PSCs with record power conversion efficiencies (PCEs) of up to 16.7% are produced by vacuum‐free deposition of all functional layers, apart from the transparent conductive electrode. This performance compares very favorably with that of control flexible PSCs comprising an evaporated gold electrode, which displays PCEs of up to 17.4%. Furthermore, the PSCs comprising a printed electrode demonstrate outstanding operational and mechanical stability, with negligible loss of PCE after 24 h of continuous 1‐sun illumination and retention of more than 90% of their initial PCE after 3000 cyclic bends.

Recent Progress Toward Commercialization of Flexible Perovskite Solar Cells: From Materials and Structures to Mechanical Stabilities

“…For example, conductive Ag paste and carbon‐based paste could be bar‐coated on PET films, forming an Ag/carbon bilayer electrode. [ 205 ] Apart from the transparent conductive electrode, FPSCs were fabricated by vacuum‐free deposition of all functional layers, with a PCE of up to 16.7%, showing comparable PCE to the device with an evaporated gold electrode (17.4%).…”

“…Lately, to avoid the influences from heat or solvent processing, a dry press deposition technique was developed for the roll‐to‐roll fabrication. [ 205 ] The pre‐deposited electrode was transferred onto the perovskite layers via mechanical pressure, without vacuum or solvent. Devices displaying PCEs of up to 16.7% were produced, marking the highest reported efficiency for a roll‐to‐roll printed FPSC comprising a vacuum‐free “back electrode.” This method provides an alternative approach to the expensive evaporated deposition of metal electrodes.…”

“…Lately, to avoid the influences from heat or solvent processing, a dry press deposition technique was developed for the roll-to-roll fabrication. [205] The pre-deposited electrode was transferred onto the perovskite layers via mechanical pressure, without vacuum or solvent. Devices displaying [243] Copyright 2018, Elsevier.…”

All‐Printed Roll‐to‐Roll Perovskite Photovoltaics Enabled by Solution‐Processed Carbon Electrode

“…Recently, the potential for a laminated electrode made up of multilayer silver and carbon stack has been demonstrated by applying the electrode onto a R2R-coated stack using a calendar press. [27] These represent important advancements toward the promise of large-area, high-volume solution-processed perovskite devices, and are summarized in Table 1. [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] However, in almost all R2R perovskite photovoltaic research to date, the final electrode deposition is achieved through evaporation of a precious and limited-resource metal.…”

“…[27] These represent important advancements toward the promise of large-area, high-volume solution-processed perovskite devices, and are summarized in Table 1. [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] However, in almost all R2R perovskite photovoltaic research to date, the final electrode deposition is achieved through evaporation of a precious and limited-resource metal. Although evaporation of gold or silver as a contact electrode enables researchers to fabricate efficient and consistent devices, this slow, expensive, wasteful process is a key barrier to perovskites leaving the lab and finding real world applications.…”