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Issue 38, 2019
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Inverted planar perovskite solar cells based on CsI-doped PEDOT:PSS with efficiency beyond 20% and small energy loss

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Abstract

PEDOT:PSS is widely used in perovskite solar cells (PSCs) as the most popular hole transporting layer (HTL). However, p-i-n type inverted planar PSCs based on the PEDOT:PSS HTL typically exhibit up to 200 mV more voltage loss compared to conventional planar PSCs (n-i-p) that generally show open circuit voltages (VOC) of around 1.1 V. In this study, we develop a simple, inexpensive and effective interfacial engineering strategy by doping PEDOT:PSS with cesium iodide (CsI) to reduce the voltage loss and achieve highly efficient inverted PSCs. SEM, AFM, and XPS measurements suggest that CsI modifies the interface between PEDOT:PSS and perovskite by reacting with PbI2 to form CsPbI3, thus facilitating interfacial contact and charge transport. Moreover, after CsI-modification (CsI-PEDOT:PSS), the hole transport properties of PEDOT:PSS and the hole extraction are enhanced, while the energy levels are more favorable and charge recombination is suppressed. Importantly, compared to pristine PEDOT:PSS that suffers from a large non-radiative recombination loss (0.375 V), CsI-PEDOT:PSS makes the device to realize an impressively low non-radiative voltage loss (only 0.287 V). As a result, inverted PSCs based on CsI-PEDOT:PSS show a small voltage loss, an excellent power conversion efficiency (PCE) of 20.22%, and no hysteresis and achieve a high VOC (1.084 V), while the control device without CsI shows an inferior efficiency of 16.57%. Both the high VOC and PCE are an improvement over literature data on modified PEDOT:PSS-based inverted PSCs.

Graphical abstract: Inverted planar perovskite solar cells based on CsI-doped PEDOT:PSS with efficiency beyond 20% and small energy loss

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Supplementary files

Article information


Submitted
16 Aug 2019
Accepted
02 Sep 2019
First published
05 Sep 2019

J. Mater. Chem. A, 2019,7, 21662-21667
Article type
Communication

Inverted planar perovskite solar cells based on CsI-doped PEDOT:PSS with efficiency beyond 20% and small energy loss

K. Jiang, F. Wu, G. Zhang, P. C. Y. Chow, C. Ma, S. Li, K. S. Wong, L. Zhu and H. Yan, J. Mater. Chem. A, 2019, 7, 21662
DOI: 10.1039/C9TA08995K

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