Division and generation of a clean heart in a perovskite solar cell

If you are in the science field and have a particular interest in Energy, then you are more than likely to have heard of perovskite solar cells. These devices which are set to change the way we power our homes, etc. have grown from strength to strength from 3.8% efficiency in 2009 to 22% in 2016. It is another light harvesting system which is able to generate electricity, but how does this happen? and what has this got to do with the heart?

In any solar cell (e.g. dye sensitised solar cells), the most important thing is that light comes into the system, electrons are photo-generated (generated by light) and they flow freely around a circuit = electricity! The stages by which an electron transitions from a bound state to freely moving around a circuit happens in different ways depending on the system. In perovskite solar cells one way is via a thin film solar cell, which is a layered system consisting of a p-type layer, an n-type layer and a perovskite structured material in the middle (see figures below).

Perovskite solar cell – image from Albero et. al., J. Mater. Chem. A, 2016,4, 4353-4364 (left). Perovskite structure – image from Eames et.al. Nature Communications, 2015,6, 7497 (right).

When light enters, each perovskite molecule will divide into an electron and a “positive hole”, which is essentially the molecule without the negative electron. This occurs because the light provides enough energy for the electron to eject from the atom. This division is known as “charge generation” because a negative electron is formed and so is a positive hole. These then undergo “charge separation”, where positive holes go toward the p-type layer and electrons toward the n-type ready to power the system by flowing around a circuit = electricity.

God’s Word is quite like ‘the light’, dividing us into our bare components like the electron and the hole. The Bible says, “For the Word of God is living and active. Sharper than any double-edged sword, it pierces even to dividing to soul and spirit, joints and marrow. It is able to judge the thoughts and intentions of the heart” (Hebrews 4:12). Not only do we want God to come into us like a ray of light in a perovskite solar cell or as a double edged sword, as described in the Bible, to divide us up into who who really are, but we also want Him to generate/ create in us, a clean heart. “Create in me a clean heart, O God, and renew a steadfast spirit within me” (Psalm 51:10). That way, once God has generated that heart that is pure, it is ready to to (em)power the world like these photo-generated electrons.

For a neat video on perovskite solar cells visit: https://www.youtube.com/watch?v=crAugJXG3QA

QED.

We are all frustrated magnets trying to find which way to turn

It is so difficult when you are told to walk a path that you don’t know in the dark. You have no idea of when to turn left or right or when to just keep going straight ahead. However, this is what it is like for us as Christians- “Give careful thought to the paths for your feet and be steadfast in all your ways. Do not turn to the right or the left; keep your foot from evil.” (Proverbs 4:26-27). There can be times when we insist on ourselves to turn left or right and we become frustrated when it doesn’t work out. God knows the master plan, He sees your route, your map and knows where and why there are hindrances but we are quite like spins in a frustrated magnet not knowing the bigger picture.

Most people will remember what a bar magnet is, maybe after putting it under a piece of paper and scattering iron filings on top to see the shape it makes to correspond with its magnetic field. If you remember this far, then you’ll know that a bar magnet has a North (N) and South (S) pole which may have been coloured in red and blue, respectively and same poles repel (e.g. North-North) whilst unlike poles attract (i.e. South-North).

Bar magnet(left) denoted as an arrow (right), where the arrow head represents a North pole and the arrow tail represents a South pole. These arrows are called spins (the magnetic moment of an atom).

If you are lost then just think of the Earth, since it actually is one big bar magnet with a North and South pole.

It turns out, even atoms behave like a bar magnet (some more than others) and this is given the name “magnetic moment” or equivalently “spin”. As you can see in the diagram to the left, the spin of an atom is often denoted by an arrow but it is the same as a bar magnet.

Antiferromagnetic triangular lattice. An antiferromagnet favours spins alternating up and down. So how will each pair of interactions be satisfied when inserting a third spin (up or down)? Looking clockwise and anticlockwise you will find there is always an unfavourable pair (e.g. up up or down down). This is Frustration. Image taken from: http://discovery.ucl.ac.uk/1471485/1/BrooksBartlett_thesis.pdf, p.62

Now, lets take the triangular structure on the right here. If spins must align up and down alternately in the system, what will be the orientation of the spin labelled with a question mark?

Do you find that it is a struggle to get all three arrows alternating up and down if you follow clockwise or anticlockwise around the triangle? This is FRUSTRATION- all pairwise interactions cannot be satisfied simultaneously.

More specifically, this is geometrical frustration because of the triangular structure. If four of these same spins were placed on a square lattice then there would not be any frustration… try it!

As said before, God sees your path, God has arranged your life. Just like the “?” spin on the triangular lattice, we may not see the problem, we may not understand why we are frustrated turning left or right, but God sees the bigger picture (the whole lattice).

Take heart in the two scriptures below- knowing that God is in control and only seeks our best. Do not become frustrated, at least we have more guidance and hope than these poor spins!

Whether you turn to the right or to the left, your ears will hear a voice behind you, saying, “This is the way; walk in it.” (Isaiah 30:21).

“The Lord will make you the head, not the tail. If you pay attention to the commands of the Lord your God that I give you this day and carefully follow them, you will always be at the top, never at the bottom. Do not turn aside from any of the commands I give you today, to the right or to the left, following other gods and serving them.” (Deuteronomy 28:13-14).

Frustrated magnet- Rare Earth Pyrochlore Oxide. Ground states have 2-in 2-out of each tetrahedra with 4 out of 6 satisfied interactions for each tetrahedra. Image taken from http://discovery.ucl.ac.uk/1471485/1/BrooksBartlett_thesis.pdf p.77

When given enough energy, these Rare Earth Pyrochlore Oxides can contain effective magnetic monopoles, where one spin on each tetrahedra has flipped so there is no longer 2-in 2-out, but 3-in 1-out and 3-out 1-in. This gives a net pole.

FYI: An example of a real frustrated magnet are rare earth pyrochlore oxides (part of the corner sharing tetrahedra structure is shown in the figure above). When temperatures are very low, and we are talking about approaching absolute zero, the spins are arranged like that in the left figure (2 spins pointing in and 2 spins pointing out of each tetrahedra). In this case there are 2 pairwise interactions which are not satisfied (where satisfaction comes from a head-tail or tail-head interaction). With a little bit of energy (e.g. heat), one spin on each tetrahedra can flip and show exotic behaviour in these systems. Effective magnetic monopoles (denoted by N and S in the figure on the right) emerge as each tetrahedra now has 3-in and 1-out or 3-out and 1-in spins. Since the lattice is larger than two tetrahedra, these effective monopoles can separate throughout the lattice behaving independently of one another! This is amazing as no one has ever witnessed a North pole independent of a South pole. (More info see sections on p.62 and 69 of: http://discovery.ucl.ac.uk/1471485/1/BrooksBartlett_thesis.pdf).

QED.

 

Bad company is like aggregating nanoparticles- they make you fall

“Do not be deceived: Bad company corrupts good character.” Says 1 Corinthians 15:33. We have all been there- some people/ friends in this world have somehow enticed us into certain situations which are compromising to our beliefs. We are then left with a choice: to follow or to walk (sometimes run) away.

Colloidal nanoparticles are similar in nature (without the choice part). A beautiful, stable colloid is one in which nanoparticles are uniformly dispersed within a medium (e.g. water). This is like the suspension of gold nanoparticles in the cuvette (holder) on the left in the image below.

Light-induced flocculation of gold nanoparticles. In this study light removes the capping agent. Image taken from DOI: 10.1039/B710502A

To achieve this uniform dispersion, each of the nanoparticles should be happy to occupy their own space. This is either by: 1) surface charge repulsion, where surfaces of the nanoparticles are negatively charged (or all positively charged) and therefore repel each other, or 2) steric hindrance, where bulky functional groups on the nanoparticle’s surface reduce the opportunity of other nanoparticles getting close (aggregation). The functional groups which provide the charge or bulky groups are known as a capping agent. 

For us as Christians, that capping agent is our belief. It is what keeps us stable in our relationship with God and ideally our beliefs should not be compromised. In remaining with our belief in God, we perform at our best, which is the same as these colloidal dispersions. Magnetic iron oxide nanoparticles are being studied for cancer treatment via hyperthermia. This is where these nanoparticles are injected into the site of the tumour, an external magnetic field is applied so the nanoparticles align with the field and when the field is removed, these nanoparticles relax back to their original orientation, releasing heat along the way and blasting the tumour cells! Okay… so there is a bit more to it but the functionality is only possible in the stable form of the colloid. Please feel free to read further on magnetic hyperthermia: doi:10.1016/j.rpor.2013.09.011 (open access source from what I know).

Now when the capping agent is removed (e.g. by light or heat etc), the nanoparticles agglomerate, which is natural to them (i.e. most thermodynamically stable) since the surface tension is reduced. However, upon clustering together, their density becomes greater than the medium they are in and they flocculate together to the bottom of the holder (see the right cuvette in the image above). This creates an unstable colloid, which is not useful.

In biblical language: “Do not be unequally bound together with unbelievers [do not make mismatched alliances with them, inconsistent with your faith]. For what partnership can righteousness have with lawlessness? Or what fellowship can light have with darkness?”  (2 Corinthians 6:14, AMP). When we cosy with people who do not share our faith principles and neither respect them, we are dragged down into an unstable relationship with God. So let us be aware that our capping agent is always on before we get too close to bad company for, “how blessed is the man who does not walk in the counsel of the wicked, nor stand in the path of sinners, nor sit in the seat of scoffers! But his delight is in the law of the Lord, And in His law he meditates day and night.” (Psalm 1:1-2).

QED.

 

Fusion: where two or three are gathered

As discussed in a previous post, Fission produces energy. Energy was compared to the excitement of God and what it does in the lives of those that are saved by the Holy Spirit. We can build on this idea when considering another energy producing process known as Fusion. Unlike Fission where (unstable) atoms split,  Fusion occurs when two atoms combine together. This forms a heavier atom and energy… a lot of  energy! So much energy that even the Sun and the stars use this process to power themselves!

The Sun is formed by fusion. Image credit to: https://thenypost.files.wordpress.com/2013/12/sun.jpg

You may be thinking, what kind of atoms could combine to create so much energy? maybe something as big and complicated as Uranium (as was used in Fission)… But no, rather they consist of the smallest element known to mankind- Hydrogen! When two hydrogen atoms come together, they react to form the second smallest element, Helium. The right conditions are needed for fusion to happen: high temperature and pressure. This is key!

The fusion process should remind us of what happens in Matthew 18:20: “For where two or three gather in My Name, there am I with them”. Imagine that when two of us, little humans, full of sin and not deserving of His love, come together under the right conditions: His Name, we have the big and mighty presence of God, the power of God and all that He can do in our lives, just like the amazing energy produced to power our Sun but more! In verse 19, Jesus Himself says that if two of us can agree about anything on earth, it will be done by the Father in Heaven, that is a lot of power!

You may not feel worthy, you may feel inferior but God has given us a lot of power especially when we come together!

Please find more information about Fusion here.

QED.

Carbon captured by Jesus!*- The Kingdom of God

*This title seemed appropriate given that Wikipedia says that the composition of the human body is made up of approx 18.5% Carbon (second most abundant element after Oxygen). As though to say, we are literally captured by Jesus! 😀

Carbon Capture is the removal of carbon dioxide (CO₂). In nature, these types of system are preferably referred to as “carbon sinks”, such as the sea absorbing carbon dioxide to form carbonic acid and plants photosynthesising. “Carbon capture” refers more to the removal of carbon dioxide by some artificial means, so after burning fuels in an industrial power plant (post combustion removal), is just one example. This is important because the carbon dioxide released from these power plants contribute to the Greenhouse (or Blanket) effect causing Global Warming, so if carbon dioxide can be removed before entering the atmosphere then it is a really good thing.

There are numerous methods that scientists use/ propose for Carbon Capture and these can be found in section 4 of this review paper: http://www.sciencedirect.com/science/article/pii/S1364032114005450. For this blog post, we will stick to Polymeric Membranes and Solid Sorbents (these include zeolites, activated carbon and metal based sorbents (e.g. Calcium Oxide to form Limestone AKA Calcium Carbonate)).

The parable given by Jesus about the Sower in Matthew 13:3-9 is about four different types of people hearing and understanding the Kingdom of God. Essentially as Christians we must be sensitive to the Word of God- readily hearing and seeing (Matthew 3:16-17) and doing (James 1:22) the Word. For Jesus’ conclusion of this parable, please read Matthew 3:18-23. Lets explore this parable in a Carbon Capture context.

Behold a sower went out to sow (Matthew 13:3 ):

v.4 And as he sowed, some seed fell by the wayside; and the birds came and devoured them. This would obviously be the instance that no carbon dioxide is captured and there it goes out into the atmosphere, causing Global Warming.

Solid Sorbent: Activated Carbon. Image credited to: http://muthuvelcarbons.com/contact-us.php

v.5-6 Some fell on stony places, where they did not have much earth; and they immediately sprang up because they had no depth of earth. But when the sun was up they were scorched, and because they had no root they withered away. This is like Physisorption in Solid Sorbents (e.g. activated carbon and zeolites) where weak interactions are formed between the surface of these solids and the carbon dioxide molecules in the gas released from combustion (otherwise known as flue gas). This is all great if the surrounding temperature is low but when it gets too hot, the CO₂ unbinds from the surface and is released (desorption). In reality this desorption is good for re-using the carbon dioxide (as in capturing CO₂ and releasing it for use), but means that low operating temperatures are required, which is not the case in power plants unless the flue gas is cooled.

Polymeric Membranes. Image credited to: Membranes 2012, 2(4), 727-763; doi:10.3390/membranes2040727

v.7 And some fell among thorns, and the thorns sprang up and choked them. Polymeric membranes are like this. As their ‘membrane’ name implies, they separate molecules by allowing particular molecules to pass through (permeability), generally with respect to their molecular size. Unfortunately, the channels which enable CO₂ to pass through are also large enough for oxygen to fit (flue gas is composed of a variety of gases). Therefore, the resulting carbon captured gas is impure. The polymeric part (functional groups) on these membranes can work to increase selectivity of gas molecules by favouring some interaction with say CO₂, however, generally as the selectivity increases, the permeability decreases.

Metal based solid sorbent: Calcium Oxide. Image credited to: “Wikimedia Commons”

v.8 But others fell on good ground and yielded a crop: some a hundredfold, some sixty, some thirty. There is not a perfect solution to Carbon Capture but one of the most effective methods of capture is through Chemisorption. Unlike Physisorption, strong bonds are made between the CO₂ molecules and the solid surface (and even within the solid), to the point that a chemical reaction takes place. This happens for metal based solid sorbents such as calcium oxide, which forms limestone when reacted with carbon dioxide. The mechanism can take place at high temperatures and infact the loading of CO₂ is increased with temperature. Unlike in this parable, regenerability of the metal based solid sorbent is not so easy due to the chemical reaction, so we cannot easily recycle this solid to capture carbon dioxide several-fold (i.e it has a low number of cycles)!

We should hope that the way we are captured by Jesus is as strong as Chemisorption. That we are chemically bound and as one with Him. That even when the temperature of trials and temptations increase, our interaction with Him increases also! Let us hear His Word, be bound to His Word so it never leaves us.

HE WHO HAS EARS LET HIM HEAR!

QED.

 

 

 

Faith: the right material for high temperature conditions

There is not a person on Earth who feels they have never “gone through some fire” in life. For Christians, we call this “the testing of our faith” and it can mean that life has become too much to bear. Faith is defined as: “confidence in what we hope for and assurance about what we do not see.” (Hebrews 11:1). In essence, it is the very reason why we can believe in a God that we have never seen upfront and personal and have confidence that His Son Jesus, Our Hope and Saviour, will come back for us at the end of time.

We are also told that this same faith should be used as part of our spiritual armour in this world:- “take up the shield of faith, with which you can extinguish all the flaming arrows of the evil one” (Ephesians 6:16). This means that other than just removing the problems we face (EXTINGUISHING the flaming arrows), it should act as a BARRIER of protection against the hot and unfavourable conditions applied by the evil one. Quite like what Thermal Barrier Coatings (TBC) do for aircraft engine blades.

Thermal Barrier Coating on a Nickel superalloy turbine blade. Image credited to: http://www.virginia.edu/ms/research/wadley/high-temp.html

Aircraft engine blades, made of superalloys, operate at high temperatures of around 1250 °C and for durations greater than 10,000 hours! (If you hadn’t noticed, the Ephesians verse does not mention how long the enemy would be firing flaming darts- we’d better hope we have a good shield). The diagram above shows an “input cooling air flow”, which is keeping the nickel superalloy substrate of the turbine blade cool. On the other hand, the “insulating Thermal Barrier Coating” is in direct contact with the expanded gases directly after combustion of the aircraft fuel (that high temperature mentioned before).

We as humans are like the superalloy, we do well at being us when our lives are going well and all is cool… But as people we are good thermal conductors and when the temperature gets too hot we start to creep, then crack and eventually rupture. We need our faith in Jesus Christ, the ONLY One who can offer us hope when life seems like hell and fire even when we can not see Him, we must sense Him. The only thing that can help us to use this shield of faith and believe in its effectiveness is a strong relationship with Christ (see bond coat in diagram). As we draw near to Him, He draws near to us (James 4:8a), our faith becomes stronger and hence our shield more effective at protecting us from the fiery arrows of the enemy.

Please visit this website: http://www.virginia.edu/ms/research/wadley/high-temp.html  for more information on TBCs.

QED.

Making disciples like a fission process!

The Great Commission is so well known to many Christians. It is very clearly spelled out at the end of the Book of Matthew: “Go therefore and make disciples of all the nations, baptising them in the Name of the Father and of the Son and of the Holy Spirit…” (Matthew 28:19 NKJV).

I think that whenever we hear these words we consider and reflect on ourselves and think how few people we have saved up until this point and consider it as some sort of single-step process starting with us as individuals- I get saved and help someone else get saved. Though a reasonable thought, we forget the grandeur of this idea and the Master plan.

However, notice how this section of the Word starts in verse 18b, Jesus says, “All authority has been given to Me in heaven and on earth.”. This is to say it all starts with Me, I start this process because I have all the energy needed to do it. Jesus is like the first neutron in a fission process.

Once He got to the disciples, their hearts became like unstable nuclei (too heavy to hold this Word), just ready to burst with the Holy Spirit (more neutrons) onto the next lot of people. We know in Acts 2:41, Peter (one of the disciples) went on to save many: “…those who gladly received his word were baptised; and that day about three thousand souls were added to them” (NKJV). We also hear of Paul who caught hold of the Spirit going out and releasing the Spirit into churches all over- church in Corinth, churches of Galatia, in Ephesus, Philippi, Colosse and so on! This kind of “knock on effect” in Fission is known as a “chain reaction”.

We need to remember that we might not all be saving people (though we should try), but people all over the world are now saving people- think of how you received Him (if you have)? We are part of a much larger process than we can think or imagine. Unlike in a nuclear reactor, where scientists try to control the reaction by capturing some of these neutrons, I believe God has allowed this Great Commission to effectively be a nuclear bomb- releasing the Holy Spirit (neutrons) in all corners of the world like an out-of-control chain reaction, hitting the hearts of many!

In Fission, energy is also released. This could be perceived as the excitement of God and what it is doing in the lives of those that are saved by the Holy Spirit.

Fission can aid Fusion (a more energy-producing process). Please read the blog on Fusion for a continuation of biblical concepts in a scientific context.

QED.

Long term Christian: Climate vs Weather

Being a Christian is not particularly easy! In fact, it is really difficult, even Paul tells us that longsuffering is some trademark that we are believing in Jesus for everlasting life! (1 Timothy 1:16). There are points where we stumble in life and other times where we feel we are drowning in sin. However, we must remember that there have been good times, there have been rays of hope over time even when we feel we are in the darkness. In fact a lot of the time we feel more down because we remember Christ and feel bad. So don’t feel so “under the weather”! Don’t let that dictate to you what your walk with Christ is, but think about your climate…!

I thought I would bring this common misconception to the surface, even though it may be known by many, but it often causes a further confusion when thinking about Climate Change. So what is the difference between weather and climate? Well weather is the elements we see hourly or daily etc. such as wind, rain or a touch of sun! Whilst climate is how the weather changes over a long period of time, typically ~30 years according to the Met Office (https://youtu.be/bjwmrg__ZVw).

Image credit to: http://news.bbc.co.uk/1/hi/in_pictures/7286596.stm

Watch the video! It is really insightful and will stop you panicking about Climate Change when you see snow in summer time in the UK! 😉 This should also be a wake up call to the fact that we are imperfect and our walk in Christ will fluctuate just like the weather but God cares about our climate.

QED.