Regular Article

Solution-processed TiO₂ as a hole blocking layer in PEDOT:PSS/n-Si heterojunction solar cells

Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan

^* e-mail: saifulslm6@gmail.com

Received: 11 September 2019
Received in final form: 15 January 2020
Accepted: 7 April 2020
Published online: 9 July 2020

Abstract

The junction properties at the solution-processed titanium dioxide (TiO₂)/n-type crystalline Si(n-Si) interface were studied for poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS)/n-Si heterojunction solar cells by the steady-state photovoltaic performance and transient reverse recovery characterizations. The power conversion efficiency could be increased from 11.23% to 13.08% by adjusting the layer thickness of TiO₂ together with increasing open-circuit voltage and suppressed dark saturation current density. These findings originate from the enhancement of the carrier collection efficiency at the n-Si/cathode interface. The transient reverse recovery characterization revealed that the surface recombination velocity S was ∼375 cm/s for double TiO₂ interlayer of ∼2 nm thickness. This value was almost the same as that determined by microwave photoconductance decay measurement. These findings suggest that solution-processed TiO₂ has potential as a hole blocking layer for the crystalline Si photovoltaics.