Roles of Polymer Layer in Enhanced Photovoltaic Performance of Perovskite Solar Cells via Interface Engineering

Abstract

3.8% when first reported [1] to 22.1% [2] within a few years only. The striking rapid advances in the photovoltaic performance of PSCs are mainly attributable to the development of perovskite photoactive layer materials with superior properties, including strong light absorption from the visible to the infrared region, [3] a small exciton binding energy, [4][5][6] micrometerscale charge carrier diffusion lengths, [7,8] and high charge collection ability. [9] The PCE of PSCs based on methylammonium lead halide (CH 3 NH 3 PbX 3 ) as a model PSC device has reached 20.1% and 19.5% in inverted (p-i-n) and normal (n-i-p) architectures, [10,11] respectively. Some endeavors have been invested to improve quality of perovskite layer, such as N,Ndimethylformamide (DMF) used as a fumed source of perovskite, [12] CH 3 NH 3 I vapor and CH 3 NH 3 I employed in mixed solvents, [13][14][15] however, some urgent challenges are still to be solved for the photovoltaic performance of CH 3 NH 3 PbX 3 to be further improved. Specifically, (i) compact, void-free, and fully covered perovskite layers should be developed to reduce the leakage of photocurrent and increase the voltage in PSCs, (ii) a method of depositing perovskite layers with a flat surface is needed to improve adhesiveness to the hole transport layer, and (iii) the resistance of the perovskite phases to humidity, oxygen, and ambient Perovskite solar cells (PSCs) have attracted intensive attention as the most promising next-generation photovoltaic technology because they both enable accelerated development of photovoltaic performance and are compatible with low-cost fabrication methods. The strategy of interface engineering of the perovskite layer in PSCs is expected to result in further enhancement of the power conversion efficiency (PCE) of PSCs via minimizing the charge recombination loss. Here, a high current-voltage (stabilized power output) PCE of 20.4% (19.9%) in CH 3 NH 3 PbI 3 PSCs under reverse scanning conditions is demonstrated by incorporating a solution-processed polymer layerof poly(methyl methacrylate) (PMMA) between the perovskite photoactive layer and the hole transport layer. Moreover, steady-state and time-resolved photoluminescence spectroscopy and impedance spectroscopy are used to reveal the mechanism of the enhancement of the photovoltaic performance and its stability by the PMMA layer in a CH 3 NH 3 PbI 3 PSC device. The morphology modification, surface passivation, and protection of the perovskite layer by the insulating PMMA layer substantially contribute to the enhancement of photovoltaic performance and its stability, despite a slight reduction of the charge extraction efficiency.

Recycled Utilization of a Nanoporous Au Electrode for Reduced Fabrication Cost of Perovskite Solar Cells

“…The evaluated R rec and R HTM as a function of bias voltage under sunlight illumination condition are shown in Figure 2f. R rec and R HTM of nano‐Au/PSCs continuous decrease as the bias voltage increased, which was similar to observations in previous studies . The continuous reduction of R rec and R HTM indicates that the possibility of carrier recombination became severe and the carrier extraction ability decreases with increasing bias voltages .…”

“…R rec and R HTM of nano‐Au/PSCs continuous decrease as the bias voltage increased, which was similar to observations in previous studies . The continuous reduction of R rec and R HTM indicates that the possibility of carrier recombination became severe and the carrier extraction ability decreases with increasing bias voltages . The R rec and R HTM of nano‐Au/PSCs show slightly lower and higher values, respectively, as compared to those in the evap‐Au/PSCs, as shown in Figure S4d–f (Supporting Information).…”

“…Figure 2e and Figure S4e (Supporting Information) show the Nyquist plots of the nano‐ and evap‐Au/PSCs. The impedance spectra consisted of two features in the high‐ and low‐frequency regions derived from the contributions of carrier transport from perovskite to the HTL and the carrier recombination process, respectively. The equivalent circuit to reproduce the impedance spectra is shown in the insets of Figure 2e and Figure S4e (Supporting Information).…”

A Purified, Solvent‐Intercalated Precursor Complex for Wide‐Process‐Window Fabrication of Efficient Perovskite Solar Cells and Modules

“…[29] Our previous contributions to the development of highefficiency perovskite solar cells include the introduction of purified PbX 2 (X = I, Br,C l) precursor materials,n ow commercially available from Tokyo Chemical Industry Co., Ltd. (TCI). [2,23] Am ixed DMF/DMSO solvent is used to balance the high solubility of the starting materials in DMF with the longer film drying times attained in low-volatility solvents,s uch as DMSO. In this method, ap recursor solution is made from methylammonium iodide and lead iodide dissolved in a3:1 mixture of the solvents N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO).…”

“…Towards the end of the spin program, toluene antisolvent is dripped onto the spinning film to promote the precipitation of as olid intermediate phase,w hich is later transformed into perovskite by thermal annealing. [2,23] Am ixed DMF/DMSO solvent is used to balance the high solubility of the starting materials in DMF with the longer film drying times attained in low-volatility solvents,s uch as DMSO. [21,[31][32][33] Drying time is an important process parameter, since the antisolvent addition must be performed while the film is still wet (see Figure S1 in the Supporting Information).…”