Depth‐Dependent Post‐Treatment for Reducing Voltage Loss in Printable Mesoscopic Perovskite Solar Cells

Abstract

The printable mesoscopic perovskite solar cells consisting of a double layer of metal oxides covered by a porous carbon film have attracted attention due to their industrialization advantages. However, the tens‐of‐micrometer thickness of the triple scaffold leads to a challenge for perovskite to crystallize and for the charge carriers to separate and travel to the electrode, which limits the open circuit voltage (VOC) of such devices. In this work, a depth‐dependent post‐treatment strategy is demonstrated to synergistically passivate defects and tune interfacial energy band alignment. Two thiophene derivatives, namely 3‐chlorothiophene (3‐CT) and 3‐thiophene ethylenediamine (3‐TEA), are selected for the post‐treatment. Energy‐dispersive X‐ray spectroscopy proves that 3‐CT is uniformly distributed throughout the triple scaffold and effectively passivates the defects of the bulky perovskite, while 3‐TEA reacts rapidly with the loose perovskite in the carbon layer to form 2D perovskite, forming a type II energy band alignment at the perovskite/carbon interface. As a result, the defect‐assisted recombination is suppressed and the interfacial energy band is regulated, increasing the VOC to 1012 mV. The PCE of the devices is enhanced from 16.26% to 18.49%. This depth‐dependent post‐treatment strategy takes advantage of the unique structure and provides a new insight for reducing the voltage loss.

Application of Carbon Materials in Conductive Electrodes for Perovskite Solar Cells

“…[ 69 ] In addition to favorable carbon electrodes, the enhancement of photovoltaic performance can also be attributed to the optimization of the metal oxide charge transport layer, [ 70 ] the modification of the photoactive layer, [ 71,72 ] the reduction of light reflection loss [ 73 ] and the precise energy level alignment at the perovskite/carbon interface. [ 69,74 ]…”

“…The unencapsulated device maintained 94% of the peak PCE after over 2800 h of storage in air at room temperature and 50 AE 20% relative humidity. [69] In addition to favorable carbon electrodes, the enhancement of photovoltaic performance can also be attributed to the optimization of the metal oxide charge transport layer, [70] the modification of the photoactive layer, [71,72] the reduction of light reflection loss [73] and the precise energy level alignment at the perovskite/carbon interface. [69,74] Since the first publication on carbon-electrode PSCs was reported, the research on incorporating carbon electrodes into PSCs with a layer-by-layer structure quickly attracted extensive attention both at home and abroad.…”

Screen‐Printing Technology for Scale Manufacturing of Perovskite Solar Cells

“…Xiao et al used 3-chlorothiophene (3-CT) and 3-thiophene ethylenediamine (3-TEA) to passivate the defects on screen-printed perovskite film. [226] 3-TEA with larger molecule sizes could form 2D perovskite films that block the reverse transmission of electrons, while 3-CT could passivate the perovskite defects in the entire mesoporous support. This post-processing strategy effectively improves the PCE of screen-printed devices to 18.49%.…”

High‐Quality Hybrid Perovskite Thin Films by Post‐Treatment Technologies in Photovoltaic Applications

“…In contrast, the energy gap of identical perovskite became narrow upon postprocessing by FA + . [71] Moreover, the introduction of wide-bandgap (E g ) materials, [72] in situ growth of 2D perovskite capping layers, [73][74][75][76][77] and the use of interlayers with strong electric dipole moment [42,69,[78][79][80][81][82][83] at the postprocessing stage can also optimize the interfacial energy band structure and enhance V bi , thereby improving charge transport and collection in PSCs (Figure 3c).…”