Issue 12, 2016

Mesoscopic perovskite solar cells with an admixture of nanocrystalline TiO2 and Al2O3: role of interconnectivity of TiO2 in charge collection

Abstract

Perovskite solar cells with high power conversion efficiency usually employ mesoporous TiO2, however the role of the TiO2 layer has not been clearly resolved. Here we prepared MAPbI3 (MA = CH3NH3) perovskite solar cells with an admixture of nanocrystalline TiO2 and Al2O3 to investigate the role of the mesoporous TiO2 layer. The Al2O3 content was varied from 0% (pure TiO2) to 100% (pure Al2O3) with nominal composition of (1 − x)TiO2 + xAl2O3 (x = 0, 0.25, 0.5, 0.75 and 1). The photocurrent density and fill factor decreased as Al2O3 content increased, whereas the open-circuit voltage was hardly changed. Steady-state photoluminescence (PL) was less quenched as the Al2O3 content increased due to its non-electron-injecting characteristics, where a decrease in PL intensity with increasing TiO2 content was correlated to an increase in photocurrent. Electron injection to TiO2 was also evidenced by time-resolved PL and time-limited photocurrent measurements, where interconnection of TiO2 particles played an important role in charge collection. The slight change in voltage with Al2O3 content was explained by balancing the Fermi position due to a trade-off between charge recombination and the Fermi level. The results observed from the admixture mesoporous layer comprising electron-injecting and electron-non-injecting oxides suggest that electron-injection characteristics play an important role in determining photovoltaic parameters.

Graphical abstract: Mesoscopic perovskite solar cells with an admixture of nanocrystalline TiO2 and Al2O3: role of interconnectivity of TiO2 in charge collection

Article information

Article type
Paper
Submitted
01 sept. 2015
Accepted
05 nov. 2015
First published
06 nov. 2015

Nanoscale, 2016,8, 6341-6351

Mesoscopic perovskite solar cells with an admixture of nanocrystalline TiO2 and Al2O3: role of interconnectivity of TiO2 in charge collection

J. Cha, J. Lee, D. Son, H. Kim, I. Jang and N. Park, Nanoscale, 2016, 8, 6341 DOI: 10.1039/C5NR05974G

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