Title: Resolving Hysteresis in Perovskite Solar Cells with Rapid Flame-Processed Cobalt-Doped TiO₂

Abstract

To further increase the open–circuit voltage (V _oc) of perovskite solar cells (PSCs), many efforts have been devoted to doping the TiO₂ electron transport/selective layers by using metal dopants with higher electronegativity than Ti. However, those dopants can introduce undesired charge traps that hinder charge transport through TiO₂, so the improvement in the V _oc is often accompanied by an undesired photocurrent density–voltage (J–V) hysteresis problem. Herein, it is demonstrated that the use of a rapid flame doping process (40 s) to introduce cobalt dopant into TiO₂ not only solves the J–V hysteresis problem but also increases the V _oc and power conversion efficiency of both mesoscopic and planar PSCs. The reasons for the simultaneous improvements are two fold. First, the flame–doped Co–TiO₂ film forms Co–O_v (cobalt dopant–oxygen vacancy) pairs and hence reduces the number density of Ti³⁺ trap states. Second, Co doping upshifts the band structure of TiO₂, facilitating efficient charge extraction. As a result, for planar PSCs, the flame doping of Co increases the efficiency from 17.1% to 18.0% while reducing the hysteresis from 16.0% to 1.7%. Here, for mesoscopic PSCs, the flame doping of Co increases the efficiency from 18.5% to 20.0% while reducing the hysteresis frommore » 7.0% to 0.1%.« less

Authors:

Kim, Jung Kyu  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-8218-0062"

Chai, Sung Uk ^[2]; Ji, Yongfei ^[3]; Levy-Wendt, Ben ^[4]; Kim, Suk Hyun ^[3]; Yi, Yeonjin ^[2]; Heinz, Tony F. ^[3]; Nørskov, Jens K. ^[3]; Park, Jong Hyeok  ^[2];

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• Search DOE PAGES for ORCID "0000-0002-6629-3147"

Zheng, Xiaolin  ^[4]

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• Search DOE PAGES for ORCID "0000-0002-8889-7873"

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+ Show Author Affiliations

1. Sungkyunkwan Univ. (SKKU), Suwon (Republic of Korea); Stanford Univ., Stanford, CA (United States)
2. Yonsei Univ., Seoul (Republic of Korea)
3. Stanford Univ., Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)
4. Stanford Univ., Stanford, CA (United States)

Publication Date:

Wed Aug 29 00:00:00 EDT 2018

Research Org.:

SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)

Sponsoring Org.:

USDOE

OSTI Identifier:

1490881

Grant/Contract Number:  

AC02-76SF00515; 2015-22-0067; 2016R1A2A1A05005216; 2018R1D1A1B07050875; 20163010012450; 20173010013340

Resource Type:

Accepted Manuscript

Journal Name:

Advanced Energy Materials

Additional Journal Information:

Journal Volume: 8; Journal Issue: 29; Journal ID: ISSN 1614-6832

Publisher:

Wiley

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; cobalt‐doped TiO2; electron transport layer; hysteresis; perovskite solar cells; sol‐flame doping