Over 16.7% Efficiency Organic-Silicon Heterojunction Solar Cells with Solution-Processed Dopant-Free Contacts for Both Polarities

Abstract

Realization of synchronous improvement in optical management and electrical engineering is necessary to achieve high-performance photovoltaic device. However, inherent challenges are faced in organic-silicon heterojunction solar cells (HSCs) due to the poor contact property of polymer on structured silicon surface. Herein, a remarkable efficiency boost from 12.6% to over 16.7% in poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)/n-silicon (PEDOT:PSS/n-Si) HSCs by independent optimization of hole-/electron-selective contacts only relying on solution-based processes is realized. A bilayer PEDOT:PSS film with different functionalizations is utilized to synchronously realize conformal contact and effective carrier collection on textured Si surface, making the photogenerated carriers be well separated at heterojunction interface. Meanwhile, fullerene derivative is used as electron-transporting layer at the rear n-Si/Al interface to reduce the contact barrier. The study of carriers' transport and independent optimization on separately contacted layers may lead to an effective and simplified path to fabricate high-performance organic-silicon heterojunction devices.