Polyselenophene Polymers for Solar Cell Efficiency

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Bulk heterojunction polymer solar cells face limitations due to low power conversion efficiencies, which hinder their practical application, despite advantages such as low cost, ease of processing, and flexibility. Improving the power conversion efficiency (PCE) is essential for these solar cells to become cost-effective products.

Innovation Solution

Development of semiconducting polyselenophene derivatives with specific molecular structures, such as polyselenopheno[3,4-b]selenophene-co-benzodithiophene (PSeB1) and polyselenopheno[3,4-b]selenophene-co-benzodiselenophene (PSeB2), which are used as hole transporting materials with fullerene derivatives as acceptors, aiming to achieve a low bandgap for broad absorption in the solar spectrum and enhance charge separation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If conventional poly(3,4-ethylenedioxythiophene) (PEDOT) layer is used for hole transport, then device structure is simple, but electron leakage occurs from BHJ acceptor to anode and power conversion efficiency is low

Engineering Contradiction:

Improveelectron leakageVSAvoidhole transport layer structure

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The patent extracts and replaces the conventional PEDOT hole transport layer with alternative materials (nickel oxides, graphene oxides, or modified polymers with electron-blocking groups). This extraction of the problematic PEDOT layer eliminates the electron leakage pathway from the BHJ acceptor to the anode, while maintaining the necessary hole transport function through the substituted materials.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent modifies the electronic properties of the hole transport layer by introducing materials with different energy level configurations. Specifically, nickel oxides and graphene oxides provide electron-blocking capabilities through their electronic structure, while polymer modifications with electron-withdrawing groups alter the HOMO-LUMO energy levels to prevent electron injection, thereby changing the parameter of electron blocking capability without losing hole transport function.

Inventive Principle:

Principle #35Parameter changes

2Use of energy by moving object

If polymer bandgap is not optimized, then material structure is simple, but absorption spectrum is limited and power conversion efficiency is low

Engineering Contradiction:

Improvesolar spectrum absorptionVSAvoidpolymer molecular structure

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The patent employs composite polymer structures combining electron-donating units (such as benzodithiophene, benzodiselenophene) with electron-accepting units (such as thienothiophene, selenophene). This composite molecular architecture creates a balanced push-pull electronic structure that extends the absorption spectrum across a broader range of the solar spectrum while maintaining structural organization and processability.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent introduces localized electron-withdrawing groups (such as cyano, dicyanovinyl, tricyanovinyl substituents) at specific positions on the polymer backbone. These local modifications create regions of high electron affinity that facilitate charge separation and extend absorption into the red/NIR region, allowing the rest of the polymer structure to maintain its structural integrity and processing characteristics.

Inventive Principle:

Principle #3Local quality

3Power

If HOMO energy level is not lowered, then material structure is simple, but open-circuit voltage is limited and power conversion efficiency is low

Engineering Contradiction:

Improveopen-circuit voltageVSAvoidpolymer molecular structure

Core Design Contradiction:

PowerVSDevice complexity

Solution Approach 1:

The patent systematically lowers the HOMO energy level of the polymer by incorporating electron-withdrawing substituents (cyano, dicyanovinyl, tricyanovinyl groups) and electron-accepting heterocyclic units. This parameter change in the energy level configuration increases the energy difference between the polymer HOMO and the anode work function, thereby increasing the open-circuit voltage while maintaining good hole transport through the modified molecular structure.

Inventive Principle:

Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The semiconducting polymers exhibit high solar conversion efficiencies, with PCE exceeding 6%, due to effective light harvesting and improved charge transport, leading to high fill factors and enhanced solar cell performance.

Implementation Method 1

achieve a low bandgap for broad absorption in the solar spectrum

Methodology Applied

Scientific EffectLight absorption: Absorption (EM radiation)

Implementation Method 2

enhance charge separation

Methodology Applied

Scientific EffectCharge separation: Photovoltaic Effect

Data Source

PatentUS9153785B2Semiconducting polymers

Publication Date: 2015.10.06 UNIVERSITY OF CHICAGO

AI summary

Novel semiconducting photovoltaic polymers with conjugated units that provide improved solar conversion efficiency that can be used in electro-optical and electric devices. The polymers exhibit increased solar conversion efficiency in solar devices.